Quality feedback mechanism for bandwidth allocation in a switched digital video system

ABSTRACT

A method is provided which is suitable for implementation in a switched digital video content-based network, wherein a head end obtains a first group of program streams and sends to a client only a subset of the program streams selected by subscribers in a neighborhood of the client. At least one of imminence and presence of a condition of inadequate bandwidth is determined. Responsive to the determining of the at least one of imminence and presence of the condition of inadequate bandwidth, a bit rate of at least one of the subset of the program streams selected by the subscribers in the neighborhood of the client is dynamically decreased by adjusting encoding thereof, while maintaining adequate quality for the at least one of the subset of the program streams selected by the subscribers in the neighborhood of the client, based on an objective quality measure, in order to address the at least one of imminence and presence of the condition of inadequate bandwidth.

FIELD OF THE INVENTION

The present invention relates generally to the electrical, electronic,and computer arts, and more particularly relates to video contentnetworks.

BACKGROUND OF THE INVENTION

With the advent of digital communications technology, many TV programstreams are transmitted in digital formats. For example. DigitalSatellite System (DSS), Digital Broadcast Services (DBS), and AdvancedTelevision Standards Committee (ATSC) program streams are digitallyformatted pursuant to the well-known Moving Pictures Experts Group 2(MPEG-2) standard. The MPEG-2 standard specifies, among other things,the methodologies for video and audio data compression allowing formultiple programs, with different video and audio feeds, to bemultiplexed in a transport stream traversing a single transmissionchannel. A digital TV receiver may be used to decode an MPEG-2 encodedtransport stream, and extract the desired program therefrom.

The compressed video and audio data are typically carried by continuouselementary streams, respectively, which are broken into access units orpackets, resulting in packetized elementary streams (PESs). Thesepackets are identified by headers that contain time stamps forsynchronizing, and are used to form MPEG-2 transport streams. Fordigital broadcasting, multiple programs and their associated PESs aremultiplexed into a single transport stream. A transport stream has PESpackets further subdivided into short fixed-size data packets, in whichmultiple programs encoded with different clocks can be carried. Atransport stream not only includes a multiplex of audio and video PESs,but also other data such as MPEG-2 program specific information(sometimes referred to as metadata) describing the transport stream. TheMPEG-2 metadata may include a program associated table (PAT) that listsevery program in the transport stream. Each entry in the PAT points toan individual program map table (PMT) that lists the elementary streamsmaking up each program. Some programs are open, but some programs may besubject to conditional access (encryption), and this information (i.e.,whether open or subject to conditional access) is also carried in theMPEG-2 transport stream, typically as metadata.

The aforementioned fixed-size data packets in a transport stream eachcarry a packet identifier (PID) code. Packets in the same elementarystreams all have the same PID, so that a decoder can select theelementary stream(s) it needs and reject the remainder.Packet-continuity counters may be implemented to ensure that everypacket that is needed to decode a stream is received.

A video content network, such as a cable television network, may providemany different services; for example, free on demand, movies on demand,subscription video on demand, switched digital video, and the like. Inat least some instances, a user begins watching program material byrequesting establishment of a session, such as a switched digital videosession. In at least some cases, there may be inadequate bandwidth toestablish the requested new session and also maintain all existingsessions. Thus, network bandwidth allocation is of interest in manycases.

SUMMARY OF THE INVENTION

A quality feedback mechanism is disclosed for bandwidth allocation in aswitched digital video system.

In one aspect, an exemplary method, suitable for implementation in aswitched digital video content-based network, wherein a head end obtainsa first group of program streams and sends to a client only a subset ofthe program streams selected by subscribers in a neighborhood of theclient, includes the steps of determining at least one of imminence andpresence of a condition of inadequate bandwidth; and, responsive to thedetermining of the at least one of imminence and presence of thecondition of inadequate bandwidth, dynamically decreasing a bit rate ofat least one of the subset of the program streams selected by thesubscribers in the neighborhood of the client by adjusting encodingthereof, while maintaining adequate quality for the at least one of thesubset of the program streams selected by the subscribers in theneighborhood of the client, based on an objective quality measure, inorder to address the at least one of imminence and presence of thecondition of inadequate bandwidth.

In another aspect, an apparatus is provided for use in a switcheddigital video content-based network, wherein a head end obtains a firstgroup of program streams and sends to a client only a subset of theprogram streams selected by subscribers in a neighborhood of the client.The apparatus includes an encoder bank which encodes a plurality ofinput video streams into a plurality of output video streams. Theplurality of input video streams and the plurality of output videostreams correspond to the subset of program streams. The apparatus alsoincludes a video quality sensing system which determines an objectivemeasure of quality for at least the output video streams; an encodermanagement system coupled to the encoder bank and the video qualitysensing system; and a switched digital video bandwidth manager coupledto the encoder management system. The switched digital video bandwidthmanager is configured to determine, and signal to the encoder managementsystem, at least one of imminence and presence of a condition ofinadequate bandwidth in the switched digital video content-basednetwork. Responsive to the signaling, the encoder management system isconfigured to dynamically decrease a bit rate of at least one of thesubset of the program streams selected by the subscribers in theneighborhood of the client by adjusting encoding thereof, whilemaintaining, adequate quality for the at least one of the subset of theprogram streams selected by the subscribers in the neighborhood of theclient, based on communication from the video quality sensing systemindicative of the objective measure of quality, in order to address theat least one of imminence and presence of the condition of inadequatebandwidth.

As used herein. “facilitating” an action includes performing the action,making the action easier, helping to carry the action out, or causingthe action to be performed. Thus, by way of example and not limitation,instructions executing on one processor might facilitate an actioncarried out by instructions executing on a remote processor, by sendingappropriate data or commands to cause or aid the action to be performed.

One or more embodiments of the invention or elements thereof can beimplemented in the form of an article of manufacture including a machinereadable medium that contains one or more programs which when executedimplement such step(s); that is to say, a computer program productincluding a tangible computer readable recordable storage medium (ormultiple such media) with computer usable program code for performingthe method steps indicated. Furthermore, one or more embodiments of theinvention or elements thereof can be implemented in the form of anapparatus including a memory and at least one processor that is coupledto the memory and operative to perform, or facilitate performance of,exemplary method steps. Yet further, in another aspect, one or moreembodiments of the invention or elements thereof can be implemented inthe form of means for carrying out one or more of the method stepsdescribed herein; the means can include (i) hardware module(s), (ii)software module(s), or (iii) a combination of hardware and softwaremodules; any of (i)-(iii) implement the specific techniques set forthherein, and the software modules are stored in a tangiblecomputer-readable recordable storage medium (or multiple such media).

These and other features and advantages of the invention will becomeapparent from the following detailed description of illustrativeembodiments thereof, which is to be read in connection with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a functional block diagram illustrating an exemplary hybridfiber-coaxial (HFC) network configuration;

FIG. 1A is a functional block diagram illustrating one exemplary HFCcable network head-end configuration;

FIG. 1B is a functional block diagram illustrating one exemplary localservice node configuration;

FIG. 2 is a block diagram of a “switched” hybrid fiber coax cable CATVsystem useful with one or more embodiments of the present invention;

FIG. 3 illustrates selected carriers for transmitting program materialsand control messages in a forward passband of the system of FIG. 2;

FIG. 4 is a block diagram of a controller used in the system of FIG. 2;

FIG. 5 is a table used by the controller for dynamically assigning thecarriers for transmission of program materials;

FIG. 6 illustrates a data format of a request processed by thecontroller;

FIG. 7 is a flow chart illustrating a process for processing therequest;

FIG. 8 is a flow chart illustrating a process for retiring an unusedcarrier;

FIG. 9 is a functional block diagram illustrating one exemplarybroadcast switched architecture (BSA) network useful with one or moreembodiments of the present invention;

FIG. 10 is a block diagram of a set-top terminal;

FIG. 11 is a functional block diagram of a video content network with asession resource manager;

FIG. 12 shows exemplary components of a session resource manager;

FIG. 13 shows additional details of an exemplary session resourcemanager in its environment;

FIG. 14 shows a session manager to session gateway component;

FIG. 15 shows a session manager to service gateway component;

FIG. 16 shows a first exemplary session allocation;

FIG. 17 shows a second exemplary session allocation;

FIG. 18 is a block diagram of an exemplary system, according to anaspect of the invention;

FIGS. 19 and 20 are flow charts of exemplary method steps, according toan aspect of the invention; and

FIG. 21 is a block diagram of an exemplary computer system useful inimplementing at least a portion of one or more embodiments of theinvention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 illustrates a typical content-based network configuration 100.Note that one or more embodiments are particularly pertinent forswitched digital networks as discussed below. The various components ofthe network 100 include (i) one or more data and application originationpoints 102; (ii) one or more content sources 103, (iii) one or moreapplication distribution servers 104; (iv) one or more video-on-demand(VOD) servers 105, and (v) consumer (or customer) premises equipment(CPE) 106. Also included is a dynamic bandwidth allocation device(DBWAD) 1001 such as a global session resource manager, which is itselfa non-limiting example of a session resource manager, as discussedelsewhere herein. The distribution server(s) 104, VOD servers 105, DBWAD1001, and CPE(s) 106 are connected via a bearer (e.g., hybrid fibercable (HFC)) network 101. A simple architecture is shown in FIG. 1 forillustrative brevity, although it will be recognized that comparablearchitectures with multiple origination points, distribution servers,VOD servers, and/or CPE devices (as well as different networktopologies) may be utilized consistent with the invention. For example,the head-end architecture of FIG. 1A (described in greater detail below)may be used.

It should be noted at this point that in addition to a conventional HFCnetwork or a switched digital network to be discussed below, other kindsof video content networks can be employed for network 101 (e.g.fiber-to-the-home (FTTH) or fiber-to-the-curb (FTTC)).

The data/application origination point 102 comprises any medium thatallows data and/or applications (such as a VOD-based or “Watch TV”application) to be transferred to a distribution server 104 (forexample, over a suitable network, not separately numbered). This caninclude for example a third party data source, application vendorwebsite, compact disk read-only memory (CD-ROM), external networkinterface, mass storage device Redundant Arrays of Inexpensive Disks(RAID) system), etc. Such transference may be automatic, initiated uponthe occurrence of one or more specified events (such as the receipt of arequest packet or acknowledgement (ACK)), performed manually, oraccomplished in any number of other modes readily recognized by those ofordinary skill.

The application distribution server 104 comprises a computer systemwhere such applications can enter the network system. Distributionservers per se are well known in the networking arts.

The VOD server 105 comprises a computer system where on-demand contentcan be received from one or more of the aforementioned data sources 102and enter the network system. These servers may generate the contentlocally, or alternatively act as a gateway or intermediary from adistant source.

The CPE 106 includes any equipment in the customers' premises (or otherappropriate locations) that can be accessed by a distribution server104; for example, set-top terminal (STT), digital set-top box (DSTB),set-top box (STB), or simply “box,” and the like.

Referring now to FIG. 1A, one exemplary embodiment of a head-endarchitecture is described. As shown in FIG. 1A, the head-endarchitecture 150 comprises typical head-end components and servicesincluding billing module 152, subscriber management system (SMS) and CPEconfiguration management module 308, cable-modem termination system(CMTS) and out-of-band (OOB) system 156, as well as LAN(s) 158, 160placing the various components in data communication with one another.It will be appreciated that while a bar or bus LAN topology isillustrated, any number of other arrangements (e.g., ring, star, etc.)may be used consistent with the invention. It will also be appreciatedthat the head-end configuration depicted in FIG. 1A is high-level,conceptual architecture and that each multi-service operator or multiplesystem operator (MSO) may have multiple head-ends deployed using customarchitectures.

The architecture 150 of FIG. 1A further includes amultiplexer/encrypter/modulator (MEM) 162 coupled to the HFC network 101adapted to “condition” content for transmission over the network. Thedistribution servers 104 are coupled to the LAN 160, which providesaccess to the MEM 162 and network 101 via one or more file servers 170.The VOD servers 105 are coupled to the LAN 158, although otherarchitectures may be employed (such as for example where the VOD serversare associated with a core switching device such as an 802.3z GigabitEthernet device; or the VOD servers could be coupled to LAN 160). Sinceinformation is typically carried across multiple channels, the head-endshould be adapted to acquire the information for the carried channelsfrom various sources. Typically, the channels being delivered from thehead-end 150 to the CPE 106 (“downstream”) are multiplexed together inthe head-end and sent to neighborhood hubs (see FIG. 1B) via a varietyof interposed network components.

Content (e.g. audio, video, etc.) is provided in each downstream(in-band) channel associated with the relevant service group. Tocommunicate with the head-end or intermediary node (e.g., hub server),the CPE 106 may use the out-of-band (OOB) or DOCSIS® (Data Over CableService Interface Specification) channels (registered mark of CableTelevision Laboratories, Inc., 400 Centennial Parkway Louisville Colo.80027, USA) and associated protocols. The OpenCable™ ApplicationPlatform (OCAP) 1.0, 2.0, 3.0 (and subsequent) specification (CableTelevision laboratories Inc.) provides for exemplary networkingprotocols both downstream and upstream, although the invention is in noway limited to these approaches. All versions of the DOCSIS and OCAPspecifications are expressly incorporated herein by reference in theirentireties for all purposes.

It will also be recognized that multiple servers (broadcast, VOD, orotherwise) can be used, and disposed at two or more different locationsif desired, such as being part of different server “farms”. Thesemultiple servers can be used to feed one service group, or alternativelydifferent service groups. In a simple architecture, a single server isused to feed one or more service groups. In another variant, multipleservers located at the same location are used to feed one or moreservice groups. In yet another variant, multiple servers disposed atdifferent location are used to feed one or more service groups.

In some instances, material may also be obtained from a satellite feed1108; such material is demodulated and decrypted in block 1106 and fedto block 162. Conditional access system 157 may be provided for accesscontrol purposes. Network management system 1110 may provide appropriatemanagement functions. Note also that signals from MEM 162 and upstreamsignals from network 101 that have been demodulated and split in block1112 are fed to CMTS and OOB system 156.

Also included in FIG. 1A are a global session resource manager (GSRM)302, a Mystro Application Server 104A, and a business management system154, all of which are coupled to LAN 158, and discussed further below.GSRM 302 is one specific form of a DBWAD 1001 and is a non-limitingexample of a session resource manager.

As shown in FIG. 1B, the network 101 of FIGS. 1 and 1A comprises afiber/coax arrangement wherein the output of the MEM 162 of FIG. 1A istransferred to the optical domain (such as via an optical transceiver177 at the head-end 150 or further downstream). The optical domainsignals are then distributed to a fiber node 178, which furtherdistributes the signals over a distribution network 180 to a pluralityof local servicing nodes 182. This provides an effective 1:N expansionof the network at the local service end.

US Patent Publication 2003-0056217 of Paul D. Brooks, entitled“Technique for Effectively Providing Program Material in a CableTelevision System.” the complete disclosure of which is expresslyincorporated herein by reference for all purposes, describes oneexemplary broadcast switched digital architecture useful with one ormore embodiments of the present invention, although it will berecognized by those of ordinary skill that other approaches andarchitectures may be substituted. In a cable television system inaccordance with the Brooks invention, program materials are madeavailable to subscribers in a neighborhood on an as needed basis.Specifically, when a subscriber at a set-top terminal selects a programchannel to watch, the selection request is transmitted to a head end ofthe system. In response to such a request, a controller in the head enddetermines whether the material of the selected program channel has beenmade available to the neighborhood. If it has been made available, thecontroller identifies to the set-top terminal the carrier which iscarrying the requested program material, and to which the set-topterminal tunes to obtain the requested program material. Otherwise, thecontroller assigns an unused carrier to carry the requested programmaterial, and informs the set-top terminal of the identity of the newlyassigned carrier. The controller also retires those carriers assignedfor the program channels which are no longer watched by the subscribersin the neighborhood.

Note that reference is made herein, for brevity, to features of the“Brooks invention”—it should be understood that no inference should bedrawn that such features are necessarily present in all claimedembodiments of Brooks.

The Brooks invention is directed to a technique for utilizing limitednetwork bandwidth to distribute program materials to subscribers in acommunity access television (CATV) system. In accordance with the Brooksinvention, the CATV system makes available to subscribers selectedprogram channels, as opposed to all of the program channels furnished bythe system as in prior art. In the Brooks CATV system, the programchannels are provided on an as needed basis, and are selected to servethe subscribers in the same neighborhood requesting those channels.

FIG. 2 illustrates hybrid fiber coax (HFC) cable CATV system embodyingthe principles of the Brooks invention for providing program materialsto set-top terminals on the subscriber premises. As shown in FIG. 2, thesystem includes head end 150, fiber node 178, cable distribution network180, and service area node 182 which is connected to set-top terminals106-1 through 106-n in a neighborhood, where n is a predeterminednumber.

In head end 150, program material processing unit 202 receives programmaterials from various sources via satellites, terrestrial microwavetransmissions, cable, etc. The program materials are processed by unit202 to form K individual program data streams in a digital format, whereK is an integer. Each program data stream contains program material,which requires a transmission channel having a specified frequency bandfor its distribution. In order to fully appreciate the Brooks invention,the term “transmission channel” used here should not be confused with a“program channel.” A “transmission channel” signifies a designatedfrequency band through which a program data stream containing programmaterial is transmitted. On the other hand, a “program channel”signifies the source of the program material selected by a subscriber toview. For example, a subscriber may select program channel 2 to viewprogram material provided by CBS, program channel 14 to view programmaterial provided by ESPN; program channel 32 to view program materialprovided by MTV, etc. In this instance, there are K program channelscorresponding to the K program data streams.

In accordance with the Brooks invention, under control of controller212, switching unit 204 selects and switches a subset of the K programdata streams, say, p program data streams, to modulator bank 206, wherep≦K. The program data streams in the subset are selected in a mannerdescribed below. Each selected program data stream is transmittedthrough a different transmission channel after it modulates a carrierassociated with the transmission channel in a designated forwardpassband. As is well known, in the United States the designated forwardpassband for cable TV ranges from 50 MHz to 550 MHz.

FIG. 3 illustrates M carriers. C₁ through C_(M), associated with Mtransmission channels in the forward passband, respectively, which arepre-selected for use in this instance. Since the forward passband islimited in bandwidth, M in this instance represents the maximum numberof carriers or transmission channels that the forward passband canaccommodate. As shown in FIG. 3, the carrier frequency of C₁ is denotedCF₁; the carrier frequency of C₂ is denoted CF₂; . . . ; and the carrierfrequency of C_(M) is denoted CF_(M). In addition, in accordance withthe invention, a control carrier CC having a carrier frequency CCF isassigned to carry control messages by controller 212 to the set-topterminals through a control channel in the forward passband.

In prior art, each program channel is fixedly assigned to one of the Mcarriers for transmission of its program material. In addition, all ofthe program channels are simultaneously made available to each set-topterminal in a neighborhood. As a result, the number of program channelsthat a prior art CATV system can provide cannot exceed M. However, theBrooks invention overcomes the prior art limitations by dynamicallyassigning carriers to carry program materials of only those programchannels selected by the set-top terminals (or subscribers) in aneighborhood. Advantageously, the number of program channels that theinventive CATV system can provide, although not simultaneously, canexceed M. That is. K can be greater than M in this instance.

Thus, in accordance with the Brooks invention, controller 212communicates to switching unit 204 through link 216, causing unit 204 toswitch, to modulator bank 206, the selected p program data streams whichcontain the program channel materials selected aggregately by thesubscribers in the neighborhood. As long as p≦M, which is very likelystemming from the fact that the majority at a given time watch only afew particular favorite program channels, controller 212 manages toassign p carriers to carry the respective data streams. To that end,controller 212 also specifies to unit 204 the selected inputs ofmodulator bank 206 to which the p data streams are switched.

In this instance, modulator bank 206 includes conventional modulators.Each input to modulator bank 206 is fed to a different modulator formodulating the input onto one of the M carriers. The p data streams areswitched by unit 204 to the appropriate inputs of modulator bank 206 tobe modulated onto the p assigned carriers, resulting in p data signalsrepresenting the modulated carriers, respectively. In addition,controller 212 transmits control messages described below, through link214, to modulator bank 206 where a modulator modulates the controlmessages onto the aforementioned control carrier, resulting in a controlsignal representing the modulated control carrier.

Combiner 208 combines the p data signals and control signal to form acombined signal, which is fed to optical transceiver 210. The lattergenerates an optical signal representing the combined signal. Theoptical signal traverses optical fiber 213 to fiber node 178. Atransceiver (not shown) in fiber node 178 which performs the inversefunction to transceiver 210 converts the optical signal back to thecombined signal in electrical form. The combined signal traverses cabledistribution network 180 to service area node 182, where the combinedsignal is multicast to set-top terminals 106-1 through 106-n. A set-topterminal may tune to the control carrier frequency CCF and extract thecontrol signal from the received combined signal. The control signal maycontain information identifying the carrier which is assigned to carrythe program channel material selected by the set-top terminal. Based onany such information, the set-top terminal tunes to the frequency of theidentified carrier and extracts the corresponding data signal from thereceived combined signal. The selected program channel material is thenderived in a well-known manner from the extracted data signal forviewing.

Referring to FIG. 4, controller 212 includes processor 4004 ofconventional design, which is connected to memory 4006 and interface4002. In accordance with the Brooks invention, processor 4004 receives,from one or more of set-top terminals 106-1 through 106-n, requests formaterials of program channels selected thereby. Such requests areprocessed by processor 4004 in accordance with routines stored in memory4006 which are described below. It suffices to know for now that inresponse to one such request, processor 4004 causes switching unit 204to switch the program data stream corresponding to the requested programchannel to a selected input of modulator bank 206 and assigns an unusedcarrier for transmitting the data stream if processor 4004 has not doneso. In addition, processor 4004 transmits a control message receivableby the requesting set-top terminal, which includes the informationidentifying the carrier assigned by processor 4004 to carry therequested program channel material. As mentioned before, based on suchinformation, the requesting set-top terminal tunes to the frequency ofthe identified carrier to obtain the selected program channel material.

To manage the dynamic assignment of carriers for transmitting requestedprogram channel materials to each neighborhood, an assignment table isused in this instance which is stored in memory 4006. FIG. 5 illustratessuch an assignment table (denoted 5000), which includes columns 5004,5006 and 5008. Column 5004 enumerates each program channel X selectableby a subscriber through a set-top terminal, which ranges from 1 to K inthis instance. Column 5006 tracks, for each program channel X, thenumber of subscribers in the neighborhood who have selected that programchannel to watch (N_(PCHX)). Column 5008 includes entries identifyingthe carriers assigned by processor 5004 to carry the respectivematerials of program channels X. Thus, with assignment table 5000,processor 4004 has knowledge that, for example, referring to row 5011,carrier C₃ (one of the carriers C₁ through C_(M)) is assigned forprogram channel 2 (X=2) which 12 subscribers (N_(PCHX)=12) have selectedto watch. In addition, as indicated in row 5013, no subscriber(N_(PCHX)=0) has selected to watch program channel 1 (X=1). Thus, inaccordance with the Brooks invention, no carrier (Null) is assigned forprogram channel 1. That is, program channel 1 material is currently nottransmitted to service area node 182 and thus not currently madeavailable in the neighborhood.

When a subscriber at a set-top terminal selects a different programchannel to watch, a request for material of the newly-selected programchannel is sent from the set-top terminal to controller 212, as shown at218. It should be noted at this point that each of set-top terminals106-1 through 106-n is pre-assigned with an identifier for identifyingthe set-top terminal. FIG. 6 illustrates the request which includes,inter alia, STID field 6002 containing an identifier identifying therequesting set-top terminal, PCH_(NEW) field 6004 containing thenewly-selected program channel number, and PCH_(OLD) field 6006containing the previously-selected program channel number. Thus, forexample, if the subscriber changes the program channel selection fromchannel 8 to channel 2 (or in other words “deselects” channel 8 in favorof channel 2), the value of PCH_(NEW) field 6004 would be set to “8” andthat of PCH_(OLD) field 6006 would be set to “2.” If the subscriber hasjust turned on the cable TV to watch program channel 9, the value ofPCH_(NEW) field 6004 in that instance would be set to “9” and that ofPCH_(OLD) field 6006 would be set to “0.” indicating an off state.Conversely, if the subscriber who has been watching program channel 9chooses to turn off the cable TV, the value of PCH_(NEW) field 6004would be set to “0” and that of PCH_(OLD) field 6006 would be set to“9.”

Referring back to FIG. 2, the above-described request is generated bythe requesting set-top terminal, say, terminal 106-1, which incorporatesa cable modem for modulating a specified carrier in a reverse passbandwith the request data. As is well known, in the United States thereverse passband, which ranges from 5 MHz to 42 MHz, is allocated fortransmission of signals from set-top terminals to a head end to realizeinteractive services. e.g., the inventive cable TV service of Brooks.The modulated signal from terminal 106-1 representing the request datais fed to service area node 182, from where it is forwarded to fibernode 178 through cable distribution network 180. In fiber node 178, theaforementioned optical transceiver (not shown) generates an opticalsignal representing the modulated signal. The optical signal traversesoptical fiber 215 to optical transceiver 210 in head end 150. Opticaltransceiver 210 converts the optical signal back to the modulated signalin electrical form. The modulated signal is then demodulated bydemodulator 230 to recover the original request, which is fed tocontroller 212 through link 218. In response to the received request,controller 212 invokes a first routine stored in memory 4006.

Instructed by the first routine, processor 4004 reads the receivedrequest, as indicated at step 7002 in FIG. 7. At step 7004, processor4004 determines whether PCH_(NEW) field 6004 in the request has anonzero value f, 1≦f≦K. If not, i.e., the PCH_(NEW) field value is equalto “0” indicating that the subscriber's cable TV has been turned off,the routine comes to an end. Otherwise, processor 4004 at step 7006looks up, in assignment table 5000, the value of N_(PCHX) with X=f inthis case. At step 7008, processor 4004 determines whether the N_(PCHX)value just looked up equals 0. If N_(PCHX)=0, analogous to thepreviously described situation with respect to row 5013 of table 5000,no carrier has been assigned to carry the requested program channelmaterial to service area node 182. That is, the requested programmaterial is currently not made available to the neighborhood. In thatcase, processor 4004 at step 7010 assigns an unused carrier to carry therequested material of program channel X=f. The new carrier may beselected to avoid as much as possible noise and interference with othercarriers being used to optimize the cable TV quality. At step 7012,processor 4004 updates assignment table 5000 to include the identity ofthe carrier assigned for program channel X=f. Processor 4004 at step7016 communicates to switching unit 204, directing it to switch theprogram data stream associated with program channel X=f to the properinput of modulator bank 206 such that the program channel material ismodulated onto the newly-assigned carrier. At step 7018, processor 4004generates a control message responsive to the received request, which isto be read by the requesting set-top terminal, terminal 106-1 in thisinstance. The control message includes, among other information, theSTID from the request identifying terminal 106-1 which is the intendedrecipient of the message, and the identity of the assigned carriercarrying the requested program channel material. The control message istransmitted through the control channel in a manner described before andmulticast from service area node 182 to the set-top terminals in theneighborhood. In particular, terminal 106-1 is tuned to the controlchannel and reads the STID information in the control message, whichidentifies terminal 106-1 in this instance. Recognizing that it is theintended recipient of the message, terminal 106-1 goes on to read otherinformation in the message including the identity of the assignedcarrier carrying its selected program channel material. With theknowledge of the assigned carrier's identity, terminal 106-1 tunes tothe frequency of the assigned carrier to receive the selected programchannel material.

In any event, the routine proceeds from step 7018 to step 7020 whereprocessor 4004 increments the value of N_(PCHX) with X=f in assignmenttable 5000 by one, reflecting the fact that an additional subscriber (orset-top terminal) in the neighborhood has selected program channel X=fto view. Referring back to step 7008, if processor 4004 determines thatthe value of N_(PCHX) with X=f does not equal 0, i.e., at least one settop terminal currently receiving program channel X material carried by apreviously assigned carrier, the routine proceeds to step 7014.Processor 4004 at step 7014 looks up, in assignment table 5000, theidentity of the carrier previously assigned for program channel X=f. Theroutine then proceeds to step 7018 described before.

Reference should now be had to FIG. 8. After the first routine iscompleted, a second routine is preferably invoked to perform a garbagecollection function for retiring any carrier carrying program materialwhich is no longer selected by any set-top terminal in the neighborhood.Instructed by this second routine, processor 4004 at step 8004determines whether PCH_(OLD) field 6006 in the received request has anonzero value g, 1≦g≦K. If not, i.e. the PCH_(OLD) field value equal to“0” indicating that the subscriber's cable TV has just been turned on,the second routine comes to an end. Otherwise, processor 4004 at step8006 looks up, in assignment table 5000, the value of N_(PCHX) with X=gin this case. At step 8008, processor 4004 decrements the N_(PCHX) valuejust looked up by one, reflecting the fact that one fewer subscriber (orset-top terminal) in the neighborhood selected program channel X=g toview. Processor 4004 at step 8010 determines whether the resultingN_(PCHX) value equals 0. If not, the second routine comes to an end.Otherwise, if N_(PCHX)=0, i.e., program channel X=g no longer selectedby any subscriber (or set-top terminal) in the neighborhood, the secondroutine proceeds to step 8012. Processor 4004 at step 8012 searchesassignment table 5000 for the identity of the carrier assigned forprogram channel X=g. Processor 4004 at step 8014 communicates toswitching unit 204, causing unit 204 to stop switching the program datastream corresponding to program channel X=g to modulator bank 206,thereby terminating the transmission of the program data streamotherwise carried by the identified carrier. Processor 4004 at step 8016places the identified carrier in reserve by substituting the carrieridentity entry with “Null” in assignment table 5000.

In some instances, the system in FIG. 2 may be used to serve multipleneighborhoods. Furthermore, in some cases, the system of FIG. 2 canreadily accommodate what is known in the art as a picture-in-picture(PIP) feature providing simultaneous viewing of multiple programchannels. In that case, a set-top terminal supporting the PIP featurerequests materials of multiple program channels and simultaneously tunesto the assigned carriers carrying the requested program materials.

In the event that the carriers in the CATV system of FIG. 2 areoversubscribed, i.e., no available carrier can be assigned by controller212 to carry new program material requested by a set-top terminal in theneighborhood. “blocking” may be implemented such that the requestingset-top terminal is temporarily denied access to the new programmaterial. However, the requesting set-top terminal may be instructed bycontroller 212 to tune in the meantime to a pre-set channel reserved forthe blocking purposes. For example, this pre-set channel may carrycommercials, infomercials, coming movie attractions. etc. in addition toa stand-by notice informing the subscriber of the unavailability of therequested program material. Alternatively, controller 212 may transmit atext message including the stand-by notice to the requesting set-topterminal to be shown to the subscriber. In either event, as soon as acarrier becomes available, controller 212 transmits another notice tothe requesting set-top terminal to inform the subscriber of theavailability of the requested program material, followed by a controlmessage identifying the carrier newly assigned to carry such material.In response to this control message, the set-top terminal tunes to thefrequency of the identified carrier to obtain the requested programmaterial.

Moreover, the request of FIG. 6 may automatically be generated by aset-top terminal to deselect a program channel as soon as an event onthe program channel such as a movie is over. For example, by setting atime-out clock in the head end or set top terminal to track the playtime of the event, the request, with PCH_(NEW)=0, is transmitted as soonas the time-out period corresponding to the length of the event or afixed time expires. If no other set-top terminals in the sameneighborhood tune to the frequency of the carrier assigned for theprogram channel, the assigned carrier will be retired in accordance withthe Brooks invention. Thus, at an event boundary, a program channel maybe deselected based on a fixed or variable time-out period.

In some cases, if a request cannot be granted to a requesting set topterminal, due to inadequate bandwidth, a search can be carried out forone or more sessions that can be shut down to free up bandwidth; in atleast some instances, based on a suitable time-out period (e.g., fourhours).

The request for deselecting a program channel may also be automaticallygenerated by a set-top terminal in response to a lack of an audience.For example, the set-top terminal may incorporate detection technologiessuch as motion detectors, acoustic sensors and/or infrared sensors,which are used to detect presence of any viewers in front of the set-topterminal by their movement, voice and/or body heat. If it is determinedthat no viewer is present, the request for deselecting the programchannel is automatically generated by the set-top terminal.

FIG. 9 illustrates another exemplary “switched” network architecturealso useful with one or more embodiments of the present invention. Aso-called “broadcast switched architecture” or BSA network isillustrated in this exemplary embodiment.

Switching architectures allow improved efficiency of bandwidth use forordinary digital broadcast programs. Ideally, the subscriber will beunaware of any difference between programs delivered using a switchednetwork and ordinary streaming broadcast delivery.

FIG. 9 shows the implementation details of one exemplary embodiment ofthis broadcast switched network architecture. Specifically, the head-end150 contains switched broadcast control and media path functions 190,192 (the latter including staging processor 195); these elementscooperate to control and feed, respectively, downstream or edgeswitching devices 194 at the hub site which are used to selectivelyswitch broadcast streams to various service groups. A BSA server 196 isalso disposed at the hub site, and implements functions related toswitching and bandwidth conservation (in conjunction with a managemententity 198 disposed at the head-end). An optical transport ring 197 isutilized to distribute the dense wave-division multiplexed (DWDM)optical signals to each hub in an efficient fashion.

With respect to FIG. 9, note that in some current head ends (e.g., thoseusing technology from Motorola, Inc., Schaumburg, Ill. USA) there is noexplicit GSRM or digital network control system (DNCS); rather. VODvendors implement required functionality in their own proprietary way.In other head end configurations, such as in those implemented by TimeWarner Cable, Inc., New York, N.Y., USA, GSRM functionality, asdescribed herein, can be employed. Accordingly, it should be understoodthat the embodiments herein are exemplary and non-limiting, and one ormore embodiments of the invention can be implemented with a variety ofdifferent devices that are used to carry out appropriate functionality.For example, a session resource manager apparatus could be implementedin many different ways, and is not limited to the specific GSRM/SRMexamples shown in the figures.

In addition to “broadcast” content (e.g. video programming), the systemsof FIGS. 1-9 may also deliver Internet data services using the Internetprotocol (IP), although other protocols and transport mechanisms of thetype well known in the digital communication art may be substituted. Oneexemplary delivery paradigm comprises delivering MPEG-based videocontent, with the video transported to user personal computers (PCs) (orIP-based set-top boxes (STBs)) over DOCSIS channels comprising MPEG (orother video codec such as H.264 or AVC) over IP over MPEG. That is, thehigher layer MPEG or other encoded content is encapsulated using an IPprotocol, which then utilizes an MPEG packetization of the type wellknown in the art for delivery over the RF channels. In this fashion, aparallel delivery mode to the normal broadcast delivery exists; i.e.,delivery of video content both over traditional downstream quadratureamplitude modulation (QAM) channels (QAMs) to the tuner of the user'sSTB or other receiver device for viewing on the television, and also aspacketized IP data over the DOCSIS QAMs to the user's PC or otherIP-enabled device via the user's cable modern.

Referring again to FIG. 9, the IP packets associated with Internetservices are received by edge switch 194, and forwarded to the cablemodern termination system (CMTS) 199. The CMTS examines the packets, andforwards packets intended for the local network to the edge switch 194.Other packets are discarded or routed to another component. Note alsothat edge switch 194 in block 150 in FIG. 9 can, in the most generalcase, be the same or different as that shown in the hub site of FIG. 9.Also, in other embodiments, CMTS 199 could be located in a place otherthan the hub site.

The edge switch 194 forwards the packets received from the CMTS 199 tothe QAM modulator 189, which transmits the packets on one or morephysical (QAM-modulated RF) channels to the CPEs 106. The IP packets aretypically transmitted on RF channels that are different that the RFchannels used for the broadcast video and audio programming, althoughthis is not a requirement. The CPE 106 are each configured to monitorthe particular assigned RF channel (such as via a port or socketID/address, or other such mechanism) for IP packets intended for thesubscriber premises/address that they serve.

It will be appreciated that while some descriptions presented herein aredescribed in the context of Internet services that include multicast andunicast data, there is potential applicability to other types ofservices that include multicast transmission of data delivered over anetwork having multiple physical channels or even virtual or logicalchannels. For example, switching between various physical channels thatcomprise a virtual channel, can itself be conducted according to the“switched” approach. As a simple illustration, if a first virtualchannel is comprised of physical channels (e.g., QAMs) A, B and D, and asecond virtual channel is comprised of QAMs C, E and F, a cable modem(CM) or other CPE can be configured to switch between the A/B/D andC/E/F virtual channels as if they were a single QAM.

The configurations shown in FIGS. 1-9 are exemplary in nature anddifferent approaches may be used in other embodiments; such otherapproaches may have more or less functionality (for example, high speedInternet data services might be omitted in some cases).

FIG. 10 shows an example of a set-top terminal 900, which is one form ofCPE 106. A conventional “Watch TV” application (denoted 903 in FIG. 10)is installed in the set-top terminal (denoted 900) to service thoseprogram channels (or programs) afforded the traditional broadcastservice. Watch TV application 903, residing in memory 910, provides suchwell known functions as channel navigation control, channel selection inresponse to a channel change event, etc. A channel change event occurswhen a user at set-top terminal 900 issues a command to change from oneprogram channel to another. Such a command may be issued, say, using aremote control (not shown), which signal is receptive by set-topterminal 900. Memory 910 in this instance comprises one or more caches,disks, hard drives, non-volatile random access memories (NVRAMs),dynamic random access memories (DRAMs), read-only memories (ROMs),and/or Flash ROMs.

For example, in memory 910, NVRAM may be used for storage of a user'ssettings and set-top terminal configuration settings, such as parentalcontrol codes, favorite channel lineups, set-top terminal setups,channel maps, authorization tables, and FDC address assignments. DRAMmay be used for most application and operating system storagerequirements, such as stacks, heaps, graphics, interactive program guidedata, marketing data and usage data, and functions such as MPEG-2 videodecompression. DOLBY DIGITAL® (registered mark of Dolby LaboratoriesLicensing Corporation, San Francisco, Calif.) Adaptive Transfer Coding 3(AC-3) audio decoding, and video manipulation. ROM may be used forstorage of the operating system. Flash ROM may be used for storage ofresident application software, as well as patches of the operatingsystem and application software, which software and/or patches aredownloaded to set-top terminal 900 from head-end 150 after set-topterminal 900 has been deployed at the user's premises.

Processing unit 905 orchestrates the operations of set-top terminal 900.It executes instructions stored in memory 910 under the control of theoperating system. Service application manager (SAM) 907 forms part ofsuch an operating system of terminal 900. SAM 907 is responsible for,among other things, monitoring channel change events; administeringchannel, service and other tables in terminal 900; and maintaining aregistry of applications in terminal 900. One such application is theaforementioned Watch TV application 903 which is invoked to service atraditional broadcast channel (or program). Another potentialapplication is a so-called “NPVR TV” application 912 which is invoked toservice NPVR (network personal video recorder) enabled channels (orprograms), and which may be downloaded from head-end 150 to memory 910.Application 912, among other things, emulates the functionality of apersonal video recorder by responding to rewind, pause and fast-forwardcommands initiated by a user, and communicating such commands tohead-end 150 through interface 921 to perform the trick mode (i.e.rewind, pause and fast-forward) functions on programs. In addition, forexample, application 912 not only allows a user to reserve futurebroadcast programs for review, but also reserve, play or restartprogramming content that has broadcast. Interface 921 allows receipt ofin-band and out-of-band material from head end 150, as well as sendingcommunications to the head end via a reverse data channel (for example,of the kind(s) discussed above).

One or more embodiments employ session resource management (SRM)functionality to manage video-on-demand and/or switched digitalsessions. Preferably, the SRM provides an element that is compatibleacross a number of head end platforms, such as Motorola. OpenCable.Overlay (SA/Moto) and Scientific-Atlanta (SA). One exemplary embodimentof an SRM is a global session resource manager (GSRM). FIG. 11 shows anexemplary GSRM environment 300, which encompasses an interface to anexternal policy manager, switched digital video support, and third partyentitlement control message generator (ECMG) interfaces. An additionalgoal is to maintain and reuse currently available interfaces andprotocols. Interfaces into an external policy manager may beimplemented, for example, via a static XML interface or a dynamicSOAP/XML interface.

GSRM 302 interfaces with conditional access controller 157, which inturn interfaces with digital network control system 308 and TED(transactional encryption device) 310 as well as digital access controlsystem 312 and KLS (key list server) 314. Such interface may employ, forexample, open conditional access interface (OCAI) such as SOAP/RPC(remote procedure call). GSRM 302 may also interface with an externalpolicy manager 304, using, for example, extensible markup language(XML(SOAP)) as described in greater detail below. The skilled artisanwill appreciate that “SOAP” stands for Simple Object Access Protocol.Also, DNCS 308 may carry out management and CPE configuration analogousto block 308 in FIG. 1A.

Note that a TED is typically present in a system from Cisco Systems,Inc., San Jose, Calif. USA, or a system from Scientific Atlanta (nowalso part of Cisco Systems. Inc.), and manages the cryptographic keyswhile the KLS performs analogous functions in systems from Motorola.Inc. of Schaumburg, Ill., USA. These are non-limiting examples ofgeneral functionality for managing cryptographic keys. Thus, elements308, 310 are generally representative of systems from Scientific Atlantawhile elements 312, 314 are generally representative of Motorolasystems.

Furthermore, the GSRM may interface (for example, using session setupprotocol, SSP) with a business management system, such as the TimeWarner Cable MYSTRO business management system (BMS) 154. BMS 154 is inturn coupled to billing block 152. The business management system may inturn interface with an application server 104A, such as a Time WarnerCable MYSTRO application server, using, for example, interactiveservices architecture (ISA). The BMS 154 may also interface with asuitable VOD server 105, such as an ISA VOD system, again, using, forexample, ISA.

Yet further. GSRM 302 may interface with a suitable media flow block322, which may include a video staging system 195, a transcoder and/ortransrater 316, a network encryptor 324, and a number of QAMs 318.Communication with block 316 may be, for example, via a suitabletranscoder control interface, providing an interface from the GSRM to atranscoder or trans-rater to carry out MPEG manipulation, re-encoding,and the like; communication with block 162 may be, for example, viaremote procedure call (RPC) or a suitable network encrypter controlinterface from GSRM to network encrypter 324; and communication with theQAMs may be, for example, via RPC or edge QAM-C (EQUAM-C). Note that inFIG. 1A, encryption 324 and modulation 318 are combined in block 162.Element 320 is a router.

MAS 104A may be coupled to DNCS 308 or digital access control system 312as the case may be.

The skilled artisan will appreciate that a messaging interface from theGSRM to a transcoder or trans-rater device, or to a network encrypter,can be implemented, for example, using RPC (remote procedure call) orRTSP (real time streaming protocol) messaging to outline thecharacteristics of the desired code, rate, or encryption parameters. Atranscoder might, for example, convert from MPEG-2 to MPEG-4, in thecase where an end client supports MPEG-4. In the case of a trans-rateror statistical multiplexer type of device, the goal is to fit more videoprograms into a QAM, so the programs are statistically multiplexedtogether “on-the-fly.”

A suitable switched digital video server 306 may also be provided,including SDV RM (switched digital video resource manager to manageresources assigned to the SDV system) and SDV PM (switched digital videopolicy manager) functionality (not separately numbered). Communicationbetween GSRM 302 and server 306 may be implemented, for example, usingsession setup protocol server initiated session (SSP-SIS). Server 306may communicate with QAMs 318 via RPC or EQAM-C. A set top terminal orbox (STB) 106 may communicate with VOD server 105 via, for example,lightweight stream control protocol (LSCP); with SDV server 306 via, forexample, channel change protocol (CCP); and with GSRM 302 via, forexample, session setup protocol (SSP).

As shown in FIG. 12, the SRM 302 encompasses three major functions,namely, element and network manager 402, session manager 404, and policymanager 490. In the first function, the element manager 402 providesprovisioning and configuration information for the edge devices (e.g.,edge QAMS 318) and network encrypter 324. The second function 404handles the assignment of network and RF resources for devicesgenerating session requests. Additionally, the SRM 302 needs access, viaa secure interface, to the conditional access (CA) system 157 to providefor content security. The third function, policy manager 490, providesthe ability to allocate these resources based on pre-determined and realtime policies as related to the type of asset and/or program requestingbandwidth from the network, in addition to predetermined techniques thatcan be used when such policies do not apply. The internal policy manager490 receives rule-sets via an XML file and/or supports a SOAP/XMLinterface for real time policy decisions.

In some instances, the SRM functionality resides physically on the VODserver 105, while in other cases it is split between two entities, theVOD server 105 and a session resource manager of the DNCS 308.

The Element and Network Manager component 402 is responsible for anumber of functions. Listed below is an overview of the primarycomponents;

-   -   A provisioning system for edge devices, video servers, switched        digital video servers, network encrypter, network elements,        switches, and the like.    -   Monitoring of various network components to provide SRM engine        ability to make session decisions based on available resources.    -   Managing entitlement messages and conditional access keys, when        applicable.    -   Ability to provide a graphical representation of network        components and related interconnects, including setting        under/over-provisioning of interconnects.    -   Ability to provide a graphical interface 408 for designing and        managing the network topology and interfaces.

The network manager preferably constantly monitors network usage andreports congestion, failures, downed links, and the like. A significantaspect of the network manager is to provide high (for example, 99.99%)uptime of the network for the delivery of video services. In addition,the network manager is preferably able to proactively provide alternatelinks (when available) to traffic to minimize service interruptions andstream/session failures.

In a preferred embodiment, to provide the operator with suitablemonitoring capabilities, the network manager provides the ability toshow the current network utilization of any device and interconnectlinks. The information is preferably provided in a graphical manner tothe operator and highlights any troublesome or failed devices orconnections (for example, using the graphical user interface (GUI) 408.A layer representing the various communications protocols is shown at410.

As shown in FIG. 13, resource manager 406 of FIG. 12 preferably includesnetwork resource manager (NRM) 502, core resource manager (CRM) 504, andedge resource manager (ERM) 506. The NRM 502 is responsible forreceiving resource requests from the session managers (VOD 520, SDV 522.Shell 524, and so on). After the NRM receives the request, it will thenlook at what is needed to service the request (encryption, bandwidth,and the like) and then make the requests from the core and edge resourcemanagers 504, 506. The NRM 502 needs to be aware of all of the network(core and edge) resources and their state, so it can make sessionresource decisions. For instance, if an edge device does not supportencryption and the session needs to be encrypted, then the NRM must usethe appropriate core encryption device to encrypt the session.Functionally, the NRM, CRM and ERM may be bundled as one process and/orcomponent, or as separate processes and/or components. Note that RTSPstands for real-time streaming protocol. The network monitoringfunctionality is shown at 526.

With regard to policy manager 490, in one or more embodiments, withbusiness rules manager enabled, session allocation and most networkresources can be assigned based on a pre-defined set of business rules.For example, a high-definition (HD) VOD session may be given preferenceover a free on-demand session. While this is one example, the system ispreferably modular, extensible and configurable to allow operators toset the parameters of the business rules engine.

It is also preferred that an operator can determine rules and parametersfor the loading of network elements and connections. Instead of purelylooking at business rules, new techniques and static configurations maybe used for allocating resources on a per-stream and/or per-session orproduct basis. Some versions of the policy manager (PM) 490 inside theGSRM may allow for XML import of static policy rule sets. Preferably,the GSRM provides a GUI 408 for setting the policies and modifying them.The PM 490 may also support a dynamic policy interface via SOAP/XML toan external policy manager system 304.

A significant function of the session manager (SM) 404 is to provide themechanism for session requests to receive the proper conduit for thedelivery of video. The primary responsibility of the SM is for handlingDSM-CC session requests from a VOD client residing on a client device(e.g. STB, and the like). Each time a session is created, the SM mustcommunicate with policy manager 490 and resource manager 406 todetermine the best route for the session to be streamed and alsodetermine if, where, and how the session will be set up based on thesystem policies. Additionally, the GSRM will provide the applicationserver 104 with the appropriate information to determine the type ofstream to be created (e.g. MPEG-4 Advanced Video Codec (AVC)) andconditional access method. Non-limiting examples of conditional accessmethods include the Cisco PowerKEY® conditional access system(registered mark of Cisco Systems, Inc., San Jose, Calif., USA) for aset-top box or the Motorola MediaCipher™ system (mark of Motorola, Inc.of Schaumburg, Ill., USA).

The session manager also works in a split model with SDV manager 522 toreceive session requests (pre-provisioned/shell or exclusive/provision)for allocating network resources for this request. It is theresponsibility of the GSRM to provide a shell session manager to trackand manage shell session requests from an external session manager. Theshell session manager should maintain a list of granted shell sessions,even through a reboot, power outage, etc. Additionally, the shellsession manager should provide reconciliation tools for the externalsession manager (e.g. SDV server 306) and query tools for statuschecking with QAMs.

As seen in FIG. 14, in some instances, a session gateway process 1602resides on the BMS 154 and serves as the entry point for sessionmessaging from DSM-CC to ISA. The GSRM 302 forwards all VOD sessioncommunication along to the session gateway and the BMS in turn forwardsit to the service gateway 1604. FIG. 14 outlines an exemplary interfacestructure of the session gateway process residing in the BMS.

Reference should now be had to FIG. 15. In some instances, the GSRM andISA VOD infrastructure may gain certain efficiencies in session setupspeed and reliability by moving the session gateway process 1602 ontothe GSRM, as shown at 1702 in FIG. 15. The GSRM would then communicatedirectly to the service gateway 1604 on the ISA bus. Inasmuch as part ofthe client session request is a descriptor for the service gateway, theGSRM would use this descriptor to pass the appropriate session requestinformation to the referenced service gateway.

The ISA bus is primarily directed towards using Common Object RequestBroker Architecture (CORBA) for messaging the ISA interfaces. Directcommunication of the GSRM to the service gateway would require the GSRMto implement the appropriate ISA and CORBA interfaces. Otheralternatives to the CORBA interface include SOAP/XML.

It is preferred that a variety of different interfaces be supported byGSRM and the related components and processes, so as to permit interfacewith hardware and software from many manufacturers, such as Motorola.Scientific-Atlanta and Overlay (Moto/SA) systems. The aforementioned SSPreflects an implementation of the ISO/IEC 13818 MPEG-2 DSMCCspecification, incorporated herein by reference in its entirety for allpurposes.

The SRM 302 manages a pool of HFC and network resources across many edgedevices (e.g. edge QAMS 318) and reaching multiple service groups. Notethat core devices may include, for example, network encrypters,transcoders, statistical multiplexers, and the like. For the setup of aparticular session, the SRM allocates resources from the aforementionedpool. The qualified resources are determined by the service groupspecified by the STB 106. A mechanism that indicates that an edge devicehas been removed from service, and thereby its resources must be removedfrom the allocation pool, is provided in one or more embodiments. Theelement manager 402 configures the edge device with static configurationinformation such as modulation mode, transport ID (frequency), as wellas provisioning the MPEG-2 multi-program transport stream. Thisinformation must be communicated to the SRM so that is can betransmitted to the STB along with session specific information duringsession set-up.

Service applications and clients communicate to the SRM using thesession setup protocol, an implementation of DSM-CC. Certain parameterssuch as retransmission rate for the messages are not defined within thespecification. These must be defined or left as configurable parametersfor the SRM. In some instances, these messages are actually passedthrough the session gateway to provide a distributed object interfacefor the sessions.

In SSP, the client 106 sends a client session request to the GSRM 302 tobegin the session establishment. This request contains information foridentifying the service group as well as information pertinent to theserver application. The GSRM verifies the message integrity and passesit along to the server with which the session is desired (e.g. VODserver 105. BMS 152, 154, application server 104, SDV server 306). Theserver makes a server add resource request to the SRM, including theamount of downstream bandwidth. MPEG Program and server conditionalaccess. Also included is the Ethernet descriptor if the applicationdesires to indicate a preference. In another aspect, the “server addresource” request may include only a source parameter, allowing the GSRM302 to respond with the appropriate resources.

The SM will determine resource availability after consulting with theresource manager 406 and policy manager 490. If the resources areavailable, the GSRM 302 will allocate the appropriate resources andsignal an indication of success back to the server. If the systemrequires encryption, the GSRM 404 will send a suitable request for sameto the DNCS CA Manager (CAM) 157. If the requested resources areavailable, the CAM will reply with a confirmation. The GSRM 302 thenwill send the appropriate CA credentials to the client and encryptiondevice.

At this point, the server provides a response in which the IP address ofthe service entry point is specified. In case of failure, the GSRM addsthe resources back to the pool. The GSRM uses the HFC resourcesallocated from the pool to construct a confirmation including modulationmode, transport ID, bandwidth, client conditional access and serviceentry IP address. The SRM handles a client release request message toallow the client to abort in progress session setups. Once the sessionhas been created, the application server 104. SDV server 306, and/or VODSystem 105 will create the appropriate stream for the client.

The GSRM's role as the “global” resource manager places it in theposition to manage, monitor and control the network (incl. HFC)resources for sessions. To provide a robust QAM sharing ability, theGSRM should be the central arbiter between VOD and SDV sessions. SDVServer 306 will reside external to the GSRM server and will utilize theSSP-SIS extensions to request session bandwidth. The SDV server mayrequest this bandwidth using one of a few methods:

-   -   Shell session (pre-provision)    -   Exclusive session (shell or RM provisioned)    -   Combination of shell and exclusive

The GSRM is preferably agile enough to handle all these modessimultaneously from an external SDV system 306.

Since Network Resources become more valuable and scarce with eachsession request from clients and servers, the GSRM preferably provides amethod for arbitrating these requests. The GSRM sets session thresholdsbased on product type for VOD (e.g., free on demand (FOD), movies ondemand (MOD), subscription video on demand (SVOD), etc.) and switcheddigital video (SDV). The MSO can define the name of the product andamount of allowable sessions per service group. In addition, the systemprovides a way to proactively request session resources back from aclient and/or SDV manager. A ceiling can be prescribed by product and/orservice and when the ceiling is exceeded requests and/or teardowns couldbe done on the least preferable sessions (for instance. FOD). Thedescribed functionality provides a level of policy control on thesessions being allocated by the GSRM. The GSRM preferably provides theability to easily support an external policy manager 304 via a SOAP/XMLinterface that provides extended capabilities.

The Session Resource Manager functionality may reside on a singlecomponent such as a VOD server or may be spread across multiplecomponents. In one or more embodiments, the Session Resource Manager(SRM) is the central mechanism for aligning head end resources toestablish a peer-to-peer connection between the video server and the enduser's set-top box (STB). A sub-component of the SRM is the actualbandwidth allocation technique. With the addition of High DefinitionVideo-On-Demand to the current offering of Standard DefinitionVideo-On-Demand, appropriate techniques should be employed to supportthe commingling of High Definition Video-On-Demand (HDVOD) and StandardDefinition Video-On-Demand (SDVOD) content and the establishment ofQuality of Service (QoS) guarantees between the two different services.

The narrowcast bandwidth of the VOD service group is arguably the mostexpensive bandwidth within the cable system. Video server streams,transport, switching fabric, QAMs, RF-combining and distribution allcontribute to this cost, which is distributed over a relatively smallsubset of subscribers. Additionally, this narrowcast bandwidth isre-created over and over again to provide service to all subscribers.Regardless of the infrastructure or of the protocol or which componentis actually performing the allocation (Business Management System (BMS)154; Digital Network Control System (DNCS) 308 or VOD Server 105) it ispreferred, for operational predictability, that any or all of thecomponents optimize and allocate the bandwidth in the same manner.

When performing traffic model analysis, significant variables thatcontribute to the performance of the system are the probability of thearrival of the session setup request and the probability of the sessionhold-time. These variables contribute to the loading factor with respectto a blocking factor, which ultimately determines the number ofresources required to serve a given population of users.

Historically, when working with a single encode rate the system-blockingfactor was based on the VOD Service Group. With the commingling ofdifferent encode rates, a new blocking factor is introduced into thesystem. This is the QAM blocking factor, and it is based on theprobability of having enough bandwidth to support an HD session within agiven QAM. While there may be enough bandwidth within the VOD ServiceGroup to support an HD session, if it is not all available on a singleQAM channel, the HD session is blocked and the bandwidth is considered“stranded” with regard to its ability to support an HD session. Thisoccurs when the bandwidth consumption on a given QAM exceeds the maxrate of the QAM minus the HD rate or, for example, 37.5 Mbps-15 Mbpsequaling 22.5 Mbps.

Additionally, the probability of whether the next session request toarrive is either a SD or HD session factors into the allocationtechnique. This probability is based on multiple factors including HDSTB penetration rates, buy rates, demographics and content availability.The hold-time of a session will also be impacted based on the length ofHD content offered.

The allocation models presented herein represent a view of theallocation of sessions by ignoring the hold-time of sessions. Presentingthis material without representing the departure of session does notinvalidate the allocation technique as session hold-time, and thussession departure, has been factored into the allocation models. Thereason that it does not invalidate the allocation technique is that eachallocation decision is made at the time of session setup with the mostcurrent snapshot of bandwidth allocations across all QAMs within theservice group.

While the examples are centered around SD content encoded at 3.75 Mbpsand HD content at 15 Mbps the allocation technique can easily supportmultiple SD and multiple HD encode rates by tuning the variousparameters. Additionally, service groups with greater than four RFchannels are easily supported without any changes.

Non-limiting assumptions for the examples include:

-   -   1. Each VOD Service Group includes four 6 MHz RF channels        running QAM256.    -   2. The Standard Definition (SD) rate is 3.75 Mbps. The High        Definition (HD) rate is 15 Mbps or four times the SD rate. Thus,        the bandwidth requirement for HD is four times that of SD.    -   3. Every QAM256 channel has the capacity or payload to transport        37.5 Mbps of MPEG-2 video out of a total capacity of 38.8 Mbps.        The additional QAM bandwidth is reserved for overhead for        encryption, sessions, etc.    -   4. Although the specification uses sessions as a simplified unit        of measure for bandwidth, all decisions are really based on        bandwidth and not the number of sessions of a particular rate        (of course, other approaches can be used in other instances)    -   5. The bandwidth utilization and allocation within a QAM does        not experience fragmentation as occurs within RAM memory stacks.        Thus, there is not the problem of seeking a “largest free block”        as all the remainder bandwidth is available for allocation.

Several new variables are introduced in order to provide control of howbandwidth is allocated per service group. They are theVType(2)_Session_Limit and the VType(1)_Session_Limit. Control andflexibility can be attained when these two variables are used inconjunction with an optimized allocation technique.

Configuring the system with hard limits and not over-subscribing thesystem will reserve bandwidth and guarantee service for each individualservice. Configuring the system in an oversubscription model (definingthe sum of both variables to a value greater than the total capacity)allows for a floating pool of resources that will be allocated asrequests arrive. Oversubscription has the advantage that the bandwidthis not stranded through the reservation process, if there are norequests for that service, while at the same time providing QoSguarantees. The following examples illustrate this.

Example 1 VType(2)_Session_Limit=32 and VType(1)_Session_Limit=2

The hard limits reserve the bandwidth and guarantee service for bothSDVOD and HDVOD—in this case 32 SD sessions and 2 HD sessions. Even ifthere are no HD sessions and the 33rd SD session request arrives, itwill be denied.

Example 2 VType(2)_Session_Limit=40 and VType(1)_Session_Limit=8

In this totally over-subscribed example setting the variables to theirtheoretical maximum values allows the system to operate freely withoutany controls, first come first served.

Example 3 VType(2)_Session_Limit=40 and VType(1)_Session_Limit=2

This example allows the possibility of no more than two HD sessions, butdoes not guarantee them while allowing up to 40 SD sessions.

Example 4 VType(2)_Session_Limit=32 and VType(1)_Session_Limit=8

This example allows the possibility of 32 SD sessions and reservesbandwidth for two HD sessions while supporting the possibility of eightHD sessions.

The allocation technique is preferably optimized to:

-   -   Support configurability for a “Least Loaded” and a “Most Loaded”        session allocation model    -   Compromise between load balancing across QAMs and HD session        support    -   Enable lowest impact on active session in the event of failures    -   Increase the probability of having capacity for an HD session    -   Establish a mechanism to manage a QoS of SD and HD sessions        within a VOD Service Group    -   Implement business rules guaranteeing service levels for both SD        and HD sessions    -   Support multiple SD and multiple HD encode rates    -   Support varying number of channels per service group    -   Allow dynamic tuning of network utilization

To maintain parity among implementations of the technique, the followingvariables types are employed.

VType(n)_Threshold: The variable represents the upper bandwidththreshold to switch between the least loaded model to the most loadedmodel. VType(n)_Session_Limit: The variable represents the maximumnumber of simultaneous VType sessions within a VOD Service Group.VType(n)_Rate: The rate of the VType CODEC. VType(n)_Session_Count: Thevariable refers to the number of current VType Sessions. VType(n):Defines the CODEC type as one of the following HD-MPEG-2 @ 15 Mbps,SD-MPEG-2 @ 3.75 Mbps, HD-H.264 @ 7.5 Mbps, SD- H.264 @ 1.875 Mbps (theH.264 rates are only listed as an example) VType(1): HD-MPEG-2 @ 15 MbpsVType(2): SD-MPEG-2 @ 3.75 Mbps VType(3): HD-H.264 @ 7.5 Mbps VType(4):SD-H.264 @ 1.875 Mbps . . . . . . Vtype(n): CODEC @ Mbps

An initial technique only accounts for MPEG-2 CODEC streams, it beingunderstood that other CODEC and bit-rates can be defined in otherversions. In some instances, the VType(1)_Threshold may be set to maxbandwidth in a QAM minus the HD encode rate (e.g. 37.5-15=22.5). Oncethe bandwidth utilization within a QAM for a VOD Service Group reachesthis threshold, the allocation technique will start stacking sessions onthe least loaded QAM over the VType(1)_Threshold value. By manipulatingthe VType(1)_Threshold value, the system's performance can be tunedbased on the contention found in the system. By setting theVType(1)_Threshold to 37.5 Mbps (the max QAM bandwidth), the techniquewill allocate in a “least loaded” technique.

Since HD sessions require four times the amount of bandwidth whencompared to SD sessions, there needs to be a way of limiting the numberof HD sessions so that they cannot use all the bandwidth within aservice group, which can result in denial of service. Limiting thenumber of HD sessions allows for the theoretical reservation of enoughbandwidth to support SD VOD sessions. Conversely, limiting the number ofSD allows for the theoretical reservation of enough bandwidth to supportHD VOD sessions.

Reference should now be had to FIG. 16. Once the VType(1)_Threshold isreached across any QAM within a service group, the technique shouldstart stacking sessions on the QAM channel that has passedVType(1)_Threshold. This method of allocating sessions will increase theprobability of having the capacity to support an HD stream. This willallow a mix of 36 SD sessions and one HD session as shown in the figure.

In essence, the session requests that are provisioned below theVType(1)_Threshold are allocated across the QAMs within a VOD ServiceGroup in a “least loaded” model and session requests that are allocatedabove the VType(1)_Threshold are allocated in a “most loaded” model. Thefollowing are exemplary steps to allocate bandwidth:

-   -   1. Determine if the session setup request is either a        VType(1)_Rate or VType(2)_Rate    -   2. Compare the VType(2)_Session_Limit or the        VType(1)_Session_Limit to the new request type and then deny the        session setup request if it equals the session limit type (QoS        test) else    -   3. Check the bandwidth utilization across all the QAMs within a        VOD Service Group and determine the lowest bandwidth utilization    -   4. If the lowest bandwidth utilization is below the HD_Threshold        value on any QAM, then allocate the bandwidth on the least        loaded QAM that has the requested capacity available (if the        first QAM does not have the capacity try the        next—QAM1→QAM2→QAM3→QAM4→ . . . QAM#n) else    -   5. Allocate the bandwidth on the most loaded QAM above the        VType(1)_Threshold value QAM that has the requested capacity        available (if the first QAM does not have the capacity try the        next QAM—QAM1→QAM2→QAM3→QAM4→ . . . QAM#n)

By allocating sessions in the manner described above, the sessionallocation would, in one non-limiting example, appear as in FIG. 17. Inthis example:

-   -   Session 1 through 24 are below the VType(1)_Threshold and are        allocated in a “least loaded” model    -   25th SD session request is above the VType(1)_Threshold and is        allocated on the first most loaded QAM channel. In this example,        it would be on QAM1.    -   26th HD session request is above the VType(1)_Threshold and is        allocated on the first QAM with enough available bandwidth to        support the HD session. In this example, it would be on QAM2.    -   27th and 28th SD session requests are above the        VType(1)_Threshold and are allocated on the first most loaded        QAM channel. In this example, it would be on QAM1.    -   29th HD session request is above the VType(1)_Threshold and is        allocated on the first QAM with enough available bandwidth to        support the HD session. In this example, it would be on QAM3.    -   30th SD session request is above the VType(1)_Threshold and is        allocated on the first most loaded QAM channel. In this example,        it would be on QAM1.    -   31st, 32nd, 33rd and 34th SD session requests are above the        VType(1)_Threshold and are allocated on the first most loaded        QAM channel. In this example, it would be on QAM4.

Co-assigned United States Patent Application Publication No.2007/0076728 of Rieger et al., the complete disclosure of which isexpressly incorporated herein by reference in its entirety for allpurposes, discloses a self-monitoring and optimizing network apparatusand methods. In an exemplary embodiment, the network comprises abroadcast switched digital architecture, and network bandwidthallocation to multiple digital program streams is performed byprocessing historical user tuning data, which is obtained directly fromthe subscriber's consumer premises equipment (e.g., DSTB). When anincrease or decrease in bandwidth required to support certain programsis anticipated, network resource re-allocation is performedautomatically by a software process running on the switching server. Inthis fashion, speculative but “intelligent” projections of bandwidth andprogram stream requirements can be made automatically by the serversoftware, without operator intervention. The server also optionallydictates the optimal monitoring and data collection parameters to theDSTB. Historical data is stored on a CPE.

One or more embodiments manage bandwidth in a video system in anefficient manner, to enhance and preferably maximize the number ofchannels available to customers, while dynamically allocating bandwidthbased on video quality rather than an arbitrary value. It is presentlybelieved that one or more embodiments will be useful in a variety ofsettings; for example, wherever a control system receives informationregarding the quality of video and uses the same to interact with amanager that can then manage bit rate of one or more encoders. Thus, itis presently believed that one or more embodiments will be efficaciousfor any bandwidth-limited video system.

One or more instances relate to bandwidth management of a switcheddigital video system wherein from time to time, there are more demandsfor streams in the system than can currently be allowed (this conditionis known in the art as “blocking” as set forth above). One or moreembodiments allocate bandwidth via dynamic allocation based on overallsystem demand.

With reference now to FIG. 18, in an exemplary system, according to anaspect of the invention, an input objective measure 1801 and a resultobjective measure 1802 are directed to look at a program source 1804 andresult 1809 which are, respectively, the input and output of an encoderbank 1803. A synchronization and comparison engine 1806 measures thedifference between the source 1804 and the result that is being output1809 for a SDV system. This quality difference is passed to the encodermanagement system 1807 for monitoring. When the SDV bandwidth manager1805 determines that it is running low on available bandwidth, theencoder management system 1807 is directed to begin increasing availablebandwidth by reducing the bit rate of current streams. In someinstances, the increase in available (unused) bandwidth is achieved bydecreasing the quality and bit rate of the video streams alreadypresent; for example, assume that the quality of the streams has alreadybeen balanced and thus reductions in bit rate will degrade quality.

When the result 1809 (i.e. one or more streams encoded at a reduced bitrate) is compared to the source 1804, the comparison system 1806 ensuresthat the video quality does not degrade beyond predetermined minimumvalues considered acceptable. In at least some cases, comparison of theoutput to the source is desirable because it leads to the ability todegrade gracefully and decrease bits based on the incoming quality andeffectively manage the consumer experience. If an absolute value is usedinstead, without comparison of the output to the source, but there is apoor quality stream coming in, the better streams will tend to bepenalized (as opposed to the case where source and output are comparedand it is known that the poor quality stream is poor coming in and arelative offset versus the initial quality can be carried out—in such acase, the poor quality stream might not be the first selected fordegradation but some level of degradation could be employed rather thansimply degrading all the streams down to the poor value).

Note that the predetermined minimum values considered acceptable couldbe, for example, a percentage degradation from the input, an absolutevalue, or the like.

If the SDV bandwidth manager 1805 determines that the bandwidth isunderutilized, it can direct the encoder management system 1807 toincrease the video quality values, measure them at 1802, and providehigher bitrates to output streams 1809.

Thus, one or more embodiments employ objective measures to increase anddecrease the amount of bandwidth available on a program on an objectivequality basis. Instead of using static rates, dynamic rates are used topass an objective measure back and forth between the SDV bandwidthmanager 1805 and the encoder in encoder bank 1803, in order to decreasethe bandwidth on specified channels based on current needs.

Accordingly, one or more instances allow a dynamic allocation of videobandwidth to be managed by the SDV manager 1805, which determines whereit can decrease the number of bits in a single stream or group ofstreams without significantly decreasing the video quality for the userexperience. The SDV manager 1805 does this by passing one or morebandwidth parameters to encoders in encoder bank 1803 in real time todecrease the bits available on a stream or series of streams until itcreates enough free bandwidth to insert another channel. In someinstances, such bandwidth parameters include the bandwidth available tothe encoder to maximize the number of bits available to the videostream. In typical instances, the variable bit rate (VBR) is actuallyone of the specified parameters (or the only one). In other cases, thespecified parameter(s) indirectly determine the bit rate. In some cases,re-encoding from raw video is carried out. However, in some instances,quantizer scaling metrics can be employed for bit rate control.

Again, in one or more embodiments, actual encoding parameter(s) arechanged based on the fact of too much bandwidth currently or imminentlybeing utilized (e.g., a lack of bandwidth being available in terms ofthe total number of programs that need to be delivered—if using fixedvalues for video, it would be possible to run out of bandwidth if toomany different channels were being requested, but in some cases, if itis noted that bandwidth is falling below a low water mark, it ispossible to decrease the quality by decreasing the amount of bandwidthavailable to the existing video channels to get above the low watermark). In such cases (too much bandwidth currently or imminently beingutilized), one or more instances change some of the encoding parametersto somewhat degrade the channel quality, but not so much that it isobjectionable, thereby freeing up some additional bandwidth. Becausebandwidth is a scarce resource, one or more embodiments employ videoquality analysis to change the parameters of the encoder in real timewhen there are bandwidth limits (i.e., potential blocking). This permitsthe video quality to be degraded gracefully, rather than arbitrarily bysome previously-selected number, and therefore it is possible to regainbandwidth without harming the consumer experience.

One or more instances use a video quality analysis perceptual metric todetermine what can and cannot be degraded slightly. Rather than justarbitrarily assign three levels of quality (e.g., “1” is fine; “2” ismildly compromised for bandwidth; and “3” is running out of bandwidth);instead, one or more instances determine how close the network is torunning out of bandwidth and then determine what video can be degradedand how can it be degraded in real time to have minimal impact on videoquality, yet regain sufficient bandwidth to still add one or more SDVchannels. One or more embodiments do not change the resolution of thevideo; rather, they actually decrease video quality slightly.

As noted, in a SDV system, issues are sometimes encountered wherein thesystem is close to running out of bandwidth and it is desirable to avoidblocking. As noted above, there are techniques to determine if aparticular subscriber is not actually watching (e.g., if no channelchange or other remote control input for a long period of time, send a“ping” to the CPE and require a user response; if none is received,assume the channel is no longer being watched by the subscriber ofinterest) and if so, to “kill” that person's session. In one or moreembodiments, instead, choose video streams being played out to consumersand degrade quality minimally to regain enough bandwidth to add anotherchannel. As the system degrades quality, it reduces the number of bitsper second given to each consumer or set of consumers so as to be ableto slot in another program. In essence, one or more embodiments take alittle bit away from “everything” (or at least those streams that cantolerate it without significant quality degradation) so that anadditional SDV channel can be added (in some cases, choose the channelsthat have the highest current quality rating as compared to thebandwidth used, thus penalizing the highest consumers the most untiltheir video quality is on par with all others as a first pass, thenequally degrade the video across all networks in service). This type ofapproach is believed to be fairer to consumers than blocking someconsumers from watching a desired program at all.

Referring again to FIG. 18, objective measure blocks 1801, 1802 may beimplemented, for example, using known pieces of equipment that performvideo quality analysis in real time and can actually indicate how goodor bad the video is based on an existing specification from theInternational Telecommunication Union (ITU); namely, ANSI T1.801.03 1996Digital Transport of One-Way Video Signals-Parameters for ObjectivePerformance Assessment (different versions or other criteria (e.g., MOS)could be used in some cases). Objective measure blocks 1801, 1802 willrate the input and output video (for example, on a score from 1-5 withdecimals allowed) based on straightforward metrics such as blockiness,jitter, blur, jerkiness, and the like.

The skilled artisan will be familiar with the MOS (mean opinion score)measure of video quality per se. One or more embodiments examine thedifference between input (e.g., pre-encoded) and output (e.g.,post-encoded) values of MOS; frame alignment of the video is preferablycarried out in such cases to permit an “apples-to-apples” comparison.

With respect to encoder bank 1803, in at least some instances, all ofthe video is being re-encoded, which means that it enters the system atblock 1804, is taken all the way back down to uncompressed video, andthen is recompressed as needed. Video stream source 1804 is the actualsource of the video; in the non-limiting example of FIG. 18, it is anMPEG transport stream (but video from any appropriate source can behandled in one or more embodiments; see, e.g. source 102 in FIG. 1 andsatellite feed 1108 in FIG. 1A). SDV bandwidth manager 1805 is a pieceof equipment that, in essence, allocates the number of bits on a “wire”that an MSO is able to give to a video stream at any given moment, basedupon the capacity of the “wire.”

In one or more embodiments, SDV bandwidth manager 1805 is implementedusing a Cisco Universal Session and Resource Manager available fromScientific-Atlanta, Inc., 5030 Sugarloaf Parkway, Lawrenceville, Ga.30042-5447 USA, part of Cisco Systems, Inc., San Jose, Calif. USA.However, any suitable SDV session manager can be employed; for example,the switched broadcast manager available from BigBand Networks, RedwoodCity, Calif. United States, is another non-limiting example.

In general terms, the functionality of bandwidth manager 1805 could beprovided in many locations; for example, DBWAD 1001, controller 212.GSRM 302, SDV server 306. SDV manager 522, a dedicated unit in the headend 150 on LAN 158 or LAN 160, or otherwise.

Video synchronization and comparison engine 1806 is equipped to carryout frame synchronization and compare the scores before and after theencoder banks 1803 to determine what the degradation of the video is asa result of the compression methodology. Encoder management system 1807takes information from the SDV bandwidth manager 1805 (regarding howmuch bandwidth is available), takes the scores from the videosynchronization and comparison engine 1806, and then feeds informationback and forth to the encoder bank 1803 to determine which stream getsmore or less bits at any one time. Again, 1809 represents the outputstream.

In a non-limiting example, objective measure units 1801 and 1802 areservers in the head end 150 and are preferably physically located nextto the encoders 1803. In a non-limiting example, they are Dell 1RUservers or the Like. They join the stream in real time and analyze it.The encoder bank 1803 includes encoders inside a video head end 150. Thevideo stream sources 1804 may be thought of as a “cloud” of sources;typically, for an MSO, these include optic cable from a localbroadcaster or a satellite link from HBO, CNN or the like, as discussedabove. Non-limiting exemplary locations for encoders of encoder bank1803 include block 162 in FIG. 1A and block 316 in FIG. 11.

Video synchronization and comparison engine 1806 has heretoforetypically existed on the same server or other hardware as the objectivemeasure units 1801 and 1802. However, in one or more non-limitingembodiments, video synchronization and comparison engine 1806 isprovided on a separate server due to the amount of comparison required.This can be, for example, a conventional WINDOWS server.

With reference to FIG. 18, it should be noted that while objectivemeasurement per se has heretofore been known, one or more embodimentscarry out objective measurement in real time, pre- and post-encoder,with frame alignment, using a video synchronization and comparisonsystem 1806 collocated with an encoder bank 1803, and feed the resultsto encoder management system 1807 for selective bit rate degradation.

In current systems, the encoder management system 1807 is typicallylocated next to the encoder bank 1803 and typically runs the encoders inthe encoder bank 1803. A non-limiting example of a suitable system forblock 1807 is the NMX Digital Service Manager product (mark of HarmonicInc., 4300 North First Street, San Jose, Calif. 95134 U.S.A.). In somecases, system 1807 might be located within block 192 in FIG. 9. The SDVbandwidth manager 1805 runs in the head end and takes information fromthe QAMs (not shown; see examples in other figures) to determine theinstantaneous bandwidth utilization and feed such information back tothe encoder management system 1807. Thus, in one or more embodiments,other than an external video stream source, all components are in thehead end 150.

Recapitulation

Attention should now be given to the flow charts of FIGS. 19 and 20. Oneor more embodiments are useful in the context of a switched digitalvideo content-based network (for example, as described above), wherein ahead end obtains a first group of program streams and sends to a clientonly a subset of the program streams selected by subscribers in aneighborhood of the client. Such program streams include at least videostreams.

In a non-limiting example, the flow charts of FIGS. 19 and 20 representmonitoring processes which can be executed, logically, in parallel.Referring initially to the flow chart of FIG. 19, which begins in step1902, it will be appreciated that, in general terms, an exemplarymethod, according to an aspect of the invention, includes determining atleast one of imminence and presence of a condition of inadequatebandwidth, as indicated by the decision block 1904. An additional step(see, for example, blocks 1908-1916 in FIG. 19, discussed further below,for a non-limiting example) includes, responsive to determiningimminence and/or presence of the condition of inadequate bandwidth (i.e.“YES” branch of block 1904), dynamically decreasing the bit rate(directly by specifying a reduced bit rate and/or indirectly byspecifying some other parameter which results in a reduced bit rate) ofat least one of the subset of the program streams selected by thesubscribers in the neighborhood of the client by adjusting encodingthereof, while maintaining adequate quality for the stream(s) whose bitrate(s) are being reduced, based on an objective quality measure, inorder to address the aforementioned imminence and/or presence of thecondition of inadequate bandwidth.

In one or more embodiments, an additional step includes comparing thevalue of the objective quality measure prior and subsequent to theencoding (e.g., at 1801 and 1802); in such cases, the maintenance ofadequate quality (tested, for example, in decision block 1910) is basedon the comparison. Non-limiting examples include allowing some maximumpercentage of degradation or some absolute value of degradation. Atleast some instances include real-time comparing with framesynchronization.

In a non-limiting example, decision block 1910 includes ensuring thatthe objective quality measure subsequent to the encoding has notdegraded to less than a predetermined minimum value (otherwise a “NO” isreturned, and the quality is restored to an acceptable value). In somecases, the absolute value at 1809 can be compared to an absolutethreshold, rather than carrying out a comparison with the input.

In some cases, the objective quality measure takes into account any one,some, or all of blockiness, jitter, blur, and jerkiness. In someinstances, ANSI T1.801.03 1996 Digital Transport of One-Way VideoSignals-Parameters for Objective Performance Assessment is used as theobjective quality measure (different versions or other criteria (e.g.MOS) could be used in some cases).

In at least some cases, the input video streams to the encoder bank 1803are not compressed, such that the encoding step includes encodinguncompressed video (in this regard, the head end might obtain compressedvideo from one or more sources, de-compress it, and then suchuncompressed video serves as the input to the encoder bank 1803.

Note that a variety of approaches can be used for carrying out the bitrate reduction. For example, in some cases, decrease the bit rate of allcurrently-transmitted programs at once. In other cases, look for the one(or more) that exceed(s) the minimum quality measure the most, anddecrease it/them till there is enough bandwidth for another channel orit/they get to the minimum, then address the next program. In somecases, non-premium channels might be cut first. In some cases, decreasehigh quality stream(s) until all streams have similar quality and thendecrease uniformly.

Referring again back to FIG. 19, if no blocking is detected in decisionblock 1904, as per the “NO” branch, simply loop back to the beginningand continue to monitor. If actual, or imminent blocking is detected(“YES” branch of block 1904), in a non-limiting example, in step 1906,set a stream counter to identify a first stream that is to have its bitrate reduced (this could be chosen in a number of fashions; for example,the stream with the best current quality, or a stream that is not apremium channel, or some pre-defined numerical order, or the like).Then, in step 1908, dynamically decrease the bit rate for the selectedstream, checking in decision block 1910 whether quality is stillacceptable and in decision block 1912 whether the bit rate reduction hasfreed up enough bandwidth.

In the non-limiting example of FIG. 19, if the quality has degraded toomuch, as per the “NO” branch of decision block 1910, restore the qualityto an acceptable value in block 1916 and then proceed to block 1912. Ifthe bit rate has been lowered without a quality issue, simply proceeddirectly to decision block 1912, as per the “YES” branch of decisionblock 1910. In decision block 1912, determine whether the bit ratereduction for the stream currently having its bit rate reduced has freedup sufficient bandwidth to relieve the blocking condition. If so, as perthe “YES” branch of decision block 1912, return to the beginning andcontinue to monitor for any new occurrence of blocking. On the otherhand, if the bit rate reduction for the stream currently having its bitrate reduced has not freed up sufficient bandwidth to relieve theblocking condition, as per the “NO” branch of decision block 1912,proceed to step 1914 and increment the stream counter and then begindynamically decrease the bit rate for the new stream corresponding tothe incremented stream counter. Continue through the loop until adequatebandwidth is freed up. Note that incrementing the stream counter shouldbe broadly construed to cover a number of different ways for identifyingthe next stream to have its bit rate reduced.

Attention should now be given to the flow chart of FIG. 20, which beginsat 2002. In addition to checking for a blocking condition, duringoperation of the system, a parallel check can be made forunderutilization of bandwidth. Thus, in some instances, an addition step2004 includes determining imminence and/or presence of a condition ofunderutilized bandwidth. A further step (see, e.g., steps 2006-2014 inFIG. 20) includes, responsive to the determining of the imminence and/orpresence of the condition of underutilized bandwidth (i.e. “YES” branchof decision block 2004), dynamically increasing a bit rate (again,directly and/or indirectly as for the reduction) of at least one of thesubset of the program streams selected by the subscribers in theneighborhood of the client by adjusting encoding thereof in order toaddress the imminence and/or presence of the condition of underutilizedbandwidth. Note that indefinite article “a” is used in referring to thebit rate that is to be increased, since, in the general case, any one ofthe subset of the program streams selected by the subscribers in theneighborhood of the client could be selected to have its bit rateincreased, and not necessarily the one (or more) that had bit ratesreduced as described in connection with FIG. 19.

Still referring to FIG. 20, if no underutilization is detected indecision block 2004, as per the “NO” branch, simply loop back to thebeginning and continue to monitor. If actual, or imminentunderutilization is detected (“YES” branch of block 2004), in anon-limiting example, in step 2006, set a stream counter to identify afirst stream that is to have its bit rate increased (this could bechosen in a number of fashions; for example, the stream with the worstcurrent quality, or a stream that is a premium channel, or somepre-defined numerical order, or the like). Then, in step 2008,dynamically increase the bit rate for the selected stream, checking indecision block 2012 whether the bit rate increase has ended theunderutilization condition.

In the non-limiting example of FIG. 20, in decision block 2012, asnoted, determine whether the bit rate increase for the stream currentlyhaving its bit rate increased has used up sufficient bandwidth to endthe underutilization condition. If so, as per the “YES” branch ofdecision block 2012, return to the beginning and continue to monitor forany new occurrence of underutilization. On the other hand, if the bitrate increase for the stream currently having its bit rate increased hasnot used up sufficient bandwidth to end the underutilization condition,as per the “NO” branch of decision block 2012, proceed to step 2014 andincrement the stream counter and then begin dynamically increasing thebit rate for the new stream corresponding to the incremented streamcounter. Continue through the loop until adequate bandwidth is used up.Note that incrementing the stream counter should be broadly construed tocover a number of different ways for identifying the next stream to haveits bit rate increased.

Attention should now again be given again to the block diagram of FIG.18. It will be appreciated that, in general terms, an exemplaryapparatus for use in a switched digital video content-based network,wherein a head end obtains a first group of program streams and sends toa client only a subset of the program streams selected by subscribers ina neighborhood of the client, according to an aspect of the invention,includes an encoder bank 1803 which encodes a plurality of input videostreams (e.g., from one or more sources 1804) into a plurality of outputvideo streams 1809. The plurality of input video streams and theplurality of output video streams correspond to the subset of programstreams; i.e., the encoding process is carried out on those streams thatare actually being watched in the SDV system. Review of the abovediscussion of FIG. 2 may be helpful at this point.

Also included is a video quality sensing system which determines anobjective measure of quality for at least the output video streams. In anon-limiting example, the video quality sensing system includes acomparison system, such as 1806, an input objective measurement block1801 configured to measure quality of the input video streams andprovide same to the comparison system, and an output objectivemeasurement block 1802 configured to measure quality of the output videostreams and provide same to the comparison system. In some cases, block1806 also carries out frame synchronization to ensure comparison of thequality of corresponding frames in the input and output streams. Thatis, conduct a frame by frame comparison before and after the videoencoding process to ensure the video is aligned to match.

Furthermore, the apparatus includes an encoder management system 1807coupled to the encoder bank 1803 and the video quality sensing system(for example, a comparison system of the video quality sensing system,such as 1806, is coupled to the encoder management system 1807). Theapparatus even further includes a switched digital video bandwidthmanager 1805 coupled to the encoder management system 1807.

The switched digital video bandwidth manager 1805 is configured todetermine, and signal to the encoder management system 1807, imminenceand/or presence of a condition of inadequate bandwidth in the switcheddigital video content-based network. The encoder management system 1807is configured to (responsive to the signaling) dynamically decrease abit rate (again, directly and/or indirectly) of one or more of thesubset of the program streams selected by the subscribers in theneighborhood of the client, by adjusting encoding thereof. This is donewhile maintaining adequate quality for the one or more streams, based oncommunication from the video quality sensing system indicative of theobjective measure of quality, in order to address the imminence and/orpresence of the condition of inadequate bandwidth.

In one or more embodiments, the comparison system is configured tocompare, for a given one of the input video streams 1804, a value fromthe input objective measurement block 1801 to a value from the outputobjective measurement block 1802 for a corresponding one of the outputvideo streams. The maintenance of adequate quality by the encodermanagement system 1807 is based on the comparison. Non-limiting examplesinclude allowing some maximum percentage of degradation or some absolutevalue of degradation. At least some instances include real-timecomparing with frame synchronization.

In some such embodiments, the maintenance of adequate quality by theencoder management system 1807 includes ensuring that the objectivequality measure subsequent to the encoding has not degraded to less thana predetermined minimum value.

In some instances, the objective quality measure takes into account anyone, some, or all of blockiness, jitter, blur, and jerkiness. Anon-limiting example of a suitable objective quality measure is, asnoted elsewhere. ANSI T1.801.03 1996 Digital Transport of One-Way VideoSignals-Parameters for Objective Performance Assessment (differentversions or other criteria (e.g. MOS) could be used in some cases).

As alluded to elsewhere, in some cases, the encoder bank 1803 isconfigured to encode the plurality of input video streams asuncompressed video.

In some cases, the encoder management system 1807 initially decreasesthe bit rate for one or more of the subset of program streams that havea high value of the objective quality measure. Optionally, the encodermanagement system carries out the decreasing of the bit rate for suchstreams until all of the program streams have a similar value of theobjective quality measure, and then decreases the bit rate uniformly forall of the program streams.

In some instances, the exemplary apparatus can implement techniquesdescribed with respect to FIG. 20. For example, in some cases, theswitched digital video bandwidth manager 1805 is configured todetermine, and signal to the encoder management system 1807, imminenceand/or presence of a condition of underutilized bandwidth. In suchcases, responsive to the signaling, the encoder management system 1807is configured to dynamically increase a bit rate (again, directly and/orindirectly) of at least one of the subset of program streams selected bythe subscribers in the neighborhood of the client by adjusting encodingthereof, in order to address the imminence and/or presence of thecondition of underutilized bandwidth.

System and Article of Manufacture Details

The invention can employ hardware or hardware and software aspects.Software includes but is not limited to firmware, resident software,microcode, etc. One or more embodiments of the invention or elementsthereof can be implemented in the form of an article of manufactureincluding a machine readable medium that contains one or more programswhich when executed implement such step(s); that is to say, a computerprogram product including a tangible computer readable recordablestorage medium (or multiple such media) with computer usable programcode configured to implement the method steps indicated, when run on oneor more processors. Furthermore, one or more embodiments of theinvention or elements thereof can be implemented in the form of anapparatus including a memory and at least one processor that is coupledto the memory and operative to perform, or facilitate performance of,exemplary method steps.

Yet further, in another aspect, one or more embodiments of the inventionor elements thereof can be implemented in the form of means for carryingout one or more of the method steps described herein; the means caninclude (i) hardware module(s), (ii) software module(s) executing on oneor more hardware processors, or (iii) a combination of hardware andsoftware modules; any of (i)-(iii) implement the specific techniques setforth herein, and the software modules are stored in a tangiblecomputer-readable recordable storage medium (or multiple such media).Appropriate interconnections via bus, network, and the like can also beincluded.

FIG. 21 is a block diagram of a system 2100 that can implement part orall of one or more aspects or processes of the present invention,processor 2120 of which is representative of processors associated withservers, clients, set top terminals, DBWAD, SRM, GSRM, controller 212.MAS 104A, engine 1806, management system 1807, bandwidth manager 1805,the server(s) implementing blocks 1801, 1802, and any other elementswith processing capability depicted in the other figures. In one or moreembodiments, inventive steps are carried out by one or more of theprocessors in conjunction with one or more interconnecting network(s).

As shown in FIG. 21, memory 2130 configures the processor 2120 toimplement one or more aspects of the methods, steps, and functionsdisclosed herein (collectively, shown as process 2180 in FIG. 21). Thememory 2130 could be distributed or local and the processor 2120 couldbe distributed or singular. The memory 2130 could be implemented as anelectrical, magnetic or optical memory, or any combination of these orother types of storage devices. It should be noted that if distributedprocessors are employed, each distributed processor that makes upprocessor 2120 generally contains its own addressable memory space. Itshould also be noted that some or all of computer system 2100 can beincorporated into an application-specific or general-use integratedcircuit. For example, one or more method steps could be implemented inhardware in an ASIC rather than using firmware. Display 2140 isrepresentative of a variety of possible input/output devices (e.g. mice,keyboards, printers, etc.).

As is known in the art, part or all of one or more aspects of themethods and apparatus discussed herein may be distributed as an articleof manufacture that itself includes a computer readable medium havingcomputer readable code means embodied thereon. The computer readableprogram code means is operable, in conjunction with a computer system,to carry out all or some of the steps to perform the methods or createthe apparatuses discussed herein. The computer readable medium may be arecordable medium (e.g., floppy disks, hard drives, compact disks.EEPROMs, or memory cards) or may be a transmission medium a networkincluding fiber-optics, the world-wide web, cables, or a wirelesschannel using time-division multiple access, code-division multipleaccess, or other radio-frequency channel). Any medium known or developedthat can store information suitable for use with a computer system maybe used. The computer-readable code means is any mechanism for allowinga computer to read instructions and data, such as magnetic variations ona magnetic medium or height variations on the surface of a compact disk.As used herein, a tangible computer-readable recordable storage mediumis intended to encompass a recordable medium which stores instructionsand/or data in a non-transitory manner, examples of which are set forthabove, but is not intended to encompass a transmission medium ordisembodied signal.

The computer systems and servers described herein each contain a memorythat will configure associated processors to implement the methods,steps, and functions disclosed herein. Such methods, steps, andfunctions can be carried out, e.g., by processing capability onindividual elements in the other figures, or by any combination thereof.The memories could be distributed or local and the processors could bedistributed or singular. The memories could be implemented as anelectrical, magnetic or optical memory, or any combination of these orother types of storage devices. Moreover, the term “memory” should beconstrued broadly enough to encompass any information able to be readfrom or written to an address in the addressable space accessed by anassociated processor. With this definition, information on a network isstill within a memory because the associated processor can retrieve theinformation from the network.

Thus, elements of one or more embodiments of the present invention canmake use of computer technology with appropriate instructions toimplement method steps described herein.

As used herein, including the claims, a “server” includes a physicaldata processing system (for example, system 2100 as shown in FIG. 21)running a server program. It will be understood that such a physicalserver may or may not include a display, keyboard, or other input/outputcomponents.

Furthermore, it should be noted that any of the methods described hereincan include an additional step of providing a system comprising distinctsoftware modules embodied on one or more tangible computer readablestorage media. All the modules (or any subset thereof) can be on thesame medium, or each can be on a different medium, for example. Themodules can include any or all of the components shown in the figures(e.g. modules/submodules for the controller, DBWAD, SRM/GSRM, MAS,set-top terminal, billing system server, engine 1806, management system1807, bandwidth manager 1805, the server(s) implementing blocks 1801,1802, and any other elements with processing capability depicted in theother figures and/or to perform the method steps in FIGS. 19 and 20, andso on). The method steps can then be carried out using the distinctsoftware modules of the system, as described above, executing on the oneor more hardware processors. Further, a computer program product caninclude a tangible computer-readable recordable storage medium with codeadapted to be executed to carry out one or more method steps describedherein, including the provision of the system with the distinct softwaremodules. In one or more embodiments, the code is stored in anon-transitory manner.

Non-limiting examples of languages that may be used include markuplanguages (e.g., hypertext markup language (HTML), extensible markuplanguage (XML), standard generalized markup language (SGML), and thelike), C/C++, assembly language, Pascal, Java. EBIF—Extended BinaryInterchange Format language, UNIX shell scripts (for example, togenerate information to supply to the GSRM), and the like. Note thatEBIF would typically only be employed in connection with a set-top box.RTSP and/or RPC can be employed for interface protocols, for example.Furthermore, non-limiting examples of useful database software includeAccess® software (registered mark of Microsoft Corporation. Redmond,Wash., USA); Oracle® software (registered mark of Oracle InternationalCorporation, 500 Oracle Parkway, Redwood City, Calif. 94065, USA);Informix® software (registered mark of International Business MachinesCorporation, Armonk, N.Y., USA); and structured query language (SQL)software available from many sources, including Microsoft Corporation,Redmond, Wash., USA).

Accordingly, it will be appreciated that one or more embodiments of theinvention can include a computer program including computer program codemeans adapted to perform one or all of the steps of any methods orclaims set forth herein when such program is implemented on a processor,and that such program may be embodied on a tangible computer readablerecordable storage medium. Further, one or more embodiments of thepresent invention can include a processor including code adapted tocause the processor to carry out one or more steps of methods or claimsset forth herein, together with one or more apparatus elements orfeatures as depicted and described herein.

System(s) have been described herein in a form in which variousfunctions are performed by discrete functional blocks. However, any oneor more of these functions could equally well be embodied in anarrangement in which the functions of any one or more of those blocks orindeed, all of the functions thereof, are realized, for example, by oneor more appropriately programmed processors such as digital signalprocessors (DSPs). Thus, for example, switching unit 104 and modulatorbank 106 (or any other blocks, components, sub-blocks, sub-components,modules and/or sub-modules) may be realized by one or more DSPs. A DSPtypically comprises a combination of digital logic devices and othercomponents, which may be a state machine or implemented with a dedicatedmicroprocessor or micro-controller running a software program or havingfunctions programmed in firmware.

Although illustrative embodiments of the present invention have beendescribed herein with reference to the accompanying drawings, it is tobe understood that the invention is not limited to those preciseembodiments, and that various other changes and modifications may bemade by one skilled in the art without departing from the scope orspirit of the invention.

What is claimed is:
 1. A method comprising the steps of: providing aswitched digital video content-based network, wherein a head end obtainsa first group of program streams and sends to a client only a subset ofsaid program streams selected by subscribers in a neighborhood of saidclient by assigning said subset of program streams to transmissionchannels comprising dedicated frequency bands in said switched digitalvideo content-based network, determining, with a switched digital videobandwidth manager located in said head end, a condition of inadequatebandwidth in that there are or imminently will be an insufficient numberof said transmission channels to send to said client said subset of saidprogram streams; and responsive to said determining of said condition ofinadequate bandwidth by said switched digital video bandwidth manager:sending, from said switched digital video bandwidth manager to anencoder management system located in said head end, a signal indicativeof said condition of inadequate bandwidth; responsive to said signal,said encoder management system causing an encoder bank in said head endto dynamically decrease a bit rate of at least one of said subset ofsaid program streams selected by said subscribers in said neighborhoodof said client by adjusting encoding thereof, while maintaining adequatequality for said at least one of said subset of said program streamsselected by said subscribers in said neighborhood of said client, basedon an objective quality measure obtained by said encoder managementsystem from a video quality sensing system located in said head end, inorder to address said condition of inadequate bandwidth, wherein saidvideo quality sensing system comparing values of said objective qualitymeasure of said program streams determined prior to, and immediatelysubsequent to, said encoding, wherein said maintaining of said adequatequality is based on said comparing of said values of said objectivequality measure; and sending, from said encoder bank to said client,using one of said transmission channels over a wired network comprisingat least one of a fiber optic cable and a coaxial cable, said at leastone of said subset of said program streams with said dynamicallydecreased bit rate, said wired network forming at least a portion ofsaid switched digital video content-based network, wherein in said videoquality sensing system the method further comprises: measuring qualityof said program streams prior to encoding by an input objectivemeasurement block; measuring quality of said program streams immediatelysubsequent to encoding by an output objective measurement block; andcomparing, by a comparison system, for a given one of said programstreams, a value from said input objective measurement block to a valuefrom said output objective measurement block for a corresponding one ofsaid program streams, wherein said maintaining of said adequate qualityby said encoder management system is based on said comparison.
 2. Themethod of claim 1, wherein said dynamic decreasing of said bit ratecomprises said encoder management system directly specifying a reducedvalue for said bit rate.
 3. The method of claim 1, wherein said dynamicdecreasing of said bit rate comprises said encoder management systemspecifying a parameter which indirectly leads to a reduced value forsaid bit rate.
 4. The method of claim 1, wherein said maintaining ofsaid adequate quality is based on said comparing.
 5. The method of claim1, wherein said comparing comprises real-time comparing with framesynchronization.
 6. The method of claim 1, wherein said encodingcomprises encoding uncompressed video.
 7. The method of claim 1, whereinsaid maintaining of said adequate quality comprises ensuring that saidobjective quality measure subsequent to said encoding has not degradedto less than a predetermined minimum value.
 8. The method of claim 1,wherein said objective quality measure takes into account at least oneof blockiness, jitter, blur, and jerkiness.
 9. The method of claim 1,wherein said objective quality measure comprises ANSI T1.801.03.
 10. Themethod of claim 1, wherein said objective quality measure comprises meanopinion score.
 11. The method of claim 1, wherein said condition ofinadequate bandwidth is a condition of underutilized bandwidth, themethod further comprising: responsive to said determining of saidcondition of underutilized bandwidth by said switched digital videobandwidth manager: sending, from said switched digital video bandwidthmanager to said encoder management system located in said head end, asignal indicative of said condition of underutilized bandwidth;responsive to said signal, said encoder management system causing anencoder bank in said head end to dynamically increase a bit rate of atleast one of said subset of said program streams selected by saidsubscribers in said neighborhood of said client by adjusting encodingthereof, in order to address said condition of underutilized bandwidth;and sending, from said encoder bank to said client, using one of saidtransmission channels over said wired network, said at least one of saidsubset of said program streams with said dynamically increased bit rate.12. The method of claim 1, wherein said dynamic decreasing comprisesinitially decreasing said bit rate for at least one of said subset ofprogram streams having a high value of said objective quality measure.13. The method of claim 12, further comprising carrying out saiddecreasing of said bit rate for said at least one of said subset ofprogram streams having said high value of said objective qualitymeasure, until all of said program streams have a similar value of saidobjective quality measure, and then decreasing said bit rate uniformlyfor all of said program streams.
 14. The method of claim 1, wherein saidwired network comprises a hybrid fiber-coaxial arrangement.
 15. Themethod of claim 1, wherein said wired network comprises at least one ofa fiber to the home and a fiber to the curb arrangement.
 16. Anapparatus for use in a switched digital video content-based network,wherein a head end obtains a first group of program streams and sends toa client only a subset of said program streams selected by subscribersin a neighborhood of the client by assigning said subset of programstreams to transmission channels comprising dedicated frequency bands insaid switched digital video content-based network, said apparatuscomprising: an encoder bank, located in said head end, which encodes aplurality of input video streams into a plurality of output videostreams, said plurality of input video streams and said plurality ofoutput video streams corresponding to said subset of said programstreams; a video quality sensing system, located in said head end, whichdetermines an objective measure of quality for at least said outputvideo streams; an encoder management system, located in said head end,coupled to said encoder bank and said video quality sensing system; anda switched digital video bandwidth manager, located in said head end,coupled to said encoder management system; wherein: said switcheddigital video bandwidth manager is configured to determine, and signalto said encoder management system, a condition of inadequate bandwidthin the switched digital video content-based network in that there are orimminently will be an insufficient number of said transmission channelsto send to said client said subset of said program streams; responsiveto said signaling, said encoder management system is configured to causesaid encoder bank to dynamically decrease a bit rate of at least one ofsaid subset of said program streams selected by said subscribers in saidneighborhood of said client by adjusting encoding thereof, whilemaintaining adequate quality for said at least one of said subset ofsaid program streams selected by said subscribers in said neighborhoodof said client, based on communication from said video quality sensingsystem indicative of said objective measure of quality, in order toaddress said condition of inadequate bandwidth, wherein said maintainingof said adequate quality by said encoder management system comprisesensuring that said objective quality measure subsequent to said encodinghas not degraded to less than a predetermined minimum value; and saidencoder bank is configured to send to said client, using one of saidtransmission channels over a wired network comprising at least one of afiber optic cable and a coaxial cable, said at least one of said subsetof said program streams with said dynamically decreased bit rate, saidwired network forming at least a portion of said switched digital videocontent-based network, wherein said video quality sensing system in turncomprises: a comparison system coupled to said encoder managementsystem; an input objective measurement block configured to measurequality of said input video streams; and an output objective measurementblock configured to measure quality of said output video streams;wherein said comparison system is configured to compare, for a given oneof said input video streams, a value from said input objectivemeasurement block to a value from said output objective measurementblock for a corresponding one of said output video streams, wherein saidmaintaining of said adequate quality by said encoder management systemis based on said comparison.
 17. The apparatus of claim 16, wherein saiddynamic decreasing of said bit rate comprises said encoder managementsystem directly specifying a reduced value for said bit rate.
 18. Theapparatus of claim 16, wherein said dynamic decreasing of said bit ratecomprises said encoder management system specifying a parameter whichindirectly leads to a reduced value for said bit rate.
 19. The apparatusof claim 16, wherein said comparing comprises real-time comparing withframe synchronization.
 20. The apparatus of claim 16, wherein saidencoder bank is configured to encode said plurality of input videostreams as uncompressed video.
 21. The apparatus of claim 16, whereinsaid objective quality measure takes into account at least one ofblockiness, jitter, blur, and jerkiness.
 22. The apparatus of claim 16,wherein said objective quality measure comprises ANSI T1.801.03.
 23. Theapparatus of claim 16, wherein said objective quality measure comprisesmean opinion score.
 24. The apparatus of claim 16, wherein saidcondition of inadequate bandwidth is a condition of underutilizedbandwidth; and responsive to said signaling, said encoder managementsystem is configured to cause said encoder bank to dynamically increasea bit rate of at least one of said subset of said program streamsselected by said subscribers in said neighborhood of said client byadjusting encoding thereof, in order to address said condition ofunderutilized bandwidth, and to send, from said encoder bank to saidclient, using one of said transmission channels over said wired network,said at least one of said subset of said program streams with saiddynamically increased bit rate.
 25. The apparatus of claim 16, whereinsaid encoder management system initially decreases said bit rate for atleast one of said subset of program streams having a high value of saidobjective quality measure.
 26. The apparatus of claim 25, wherein saidencoder management system carries out said decreasing of said bit ratefor said at least one of said subset of program streams having said highvalue of said objective quality measure, until all of said programstreams have a similar value of said objective quality measure, and thendecreases said bit rate uniformly for all of said program streams. 27.The apparatus of claim 16, wherein said wired network which saidapparatus is configured for use in comprises a hybrid fiber-coaxialarrangement.
 28. The apparatus of claim 16, wherein said wired networkwhich said apparatus is configured for use in comprises at least one ofa fiber to the home and a fiber to the curb arrangement.
 29. Anapparatus comprising: means for, in a switched digital videocontent-based network, wherein a head end obtains a first group ofprogram streams and sends to a client only a subset of said programstreams selected by subscribers in a neighborhood of said client byassigning said subset of program streams to transmission channelscomprising dedicated frequency bands in said switched digital videocontent-based network, determining a condition of inadequate bandwidthin that there are or imminently will be an insufficient number of saidtransmission channels to send to said client said subset of said programstreams; and means for, responsive to said determining of said conditionof inadequate bandwidth, dynamically decreasing a bit rate of at leastone of said subset of said program streams selected by said subscribersin said neighborhood of said client by adjusting encoding thereof, whilemaintaining adequate quality for said at least one of said subset ofsaid program streams selected by said subscribers in said neighborhoodof said client, based on an objective quality measure, in order toaddress said condition of inadequate bandwidth, wherein values of saidobjective quality measure are determined for said program streams priorto and immediately subsequent to said encoding, wherein said maintainingof said adequate quality is based on a comparison of said values of saidobjective quality measure; and means for sending, from said means fordynamically decreasing said bit rate, to said client, using one of saidtransmission channels over a wired network comprising at least one of afiber optic cable and a coaxial cable, said at least one of said subsetof said program streams with said dynamically decreased bit rate, saidwired network forming at least a portion of said switched digital videocontent-based network, wherein said means to address said condition ofinadequate bandwidth further comprises: an input objective measurementmeans for measuring quality of said program streams prior to encoding;and an output objective measurement means for measuring quality of saidprogram streams immediately subsequent to encoding; and a comparisonmeans for comparing, for a given one of said program streams, a valuefrom said input objective measurement means to a value from said outputobjective measurement means for a corresponding one of said programstreams, wherein said maintaining of said adequate quality is based onsaid comparison.